Ask Science Lions

What is Hair and Why is it So Different Among People?

2009-03-15T13:56:00.000-07:00

Nora from Altoona, PA, wanted to know more about hair. She wrote in asking several questions about hair including: Is human hair different from animal hair? What is hair made of? Why is hair so different among the people she knows? These are all great questions about hair! So we will first learn some background about hair (e.g., structure, physical properties, and growth patterns), and then we’ll answer the questions.

We generally just think of humans having hair on the head and face but all land mammals have hairy skins. Humans are actually covered all over their bodies with hair except for the palms of the hands, soles of the feet and lips. Even though there is less visible hair on humans compared to other mammals (e.g., cats, dogs, chimpanzees), a square centimeter of human skin actually contains a greater number of follicles (or hair producing sites) than the same sized area of other mammals. The hair all over our bodies is less visible because we have lost the requirement for insulating our bodies, while mammals have not. Hair has more cosmetic value for humans but it also is for protection. For example, hair around the eyes, ears and in the nose prevent dust, insects and other debris from entering those organs where they could cause damage.

A hair is an outgrowth of the epidermis, or outermost part of the skin. Hair consists of the hair follicle and the hair shaft. The hair follicle is the point from which the hair grows, and it is a tiny cup-shaped pit buried deep in the fat of the scalp. The follicle is actually where the pigment, or color, of hair is produced. This pigment is called melanin and is carried upwards into the inner part of the hair as it grows. The hair shaft is the part of the hair that can be seen above the scalp. It consists mainly of dead cells that have turned into keratins (a special protein that is resistant to wear and tear, which is made up of very large molecules) and binding materials with small amounts of water. The center part of the hair shaft is called the cortex, while the outer layer is called the cuticle. If one thinks of the hair shaft like the trunk of a tree, then the cuticle would act as the bark protection the inner cortex where all its moisture lies. If the “bark” of the hair is well cared for, then the whole hair should remain in good condition. However, if the “bark” of the hair is damaged or stripped, then the exposed center of the hair may break.

Now that we know a little more about hair, we can answer Nora’s questions. We learned what hair is made of, but why is hair so different among the people she knows? In general, the type of hair you have is inherited from your parents. It’s actually possible that your hair type might be determined by the part of the world in which your ancestors came from. Nora also asked about animal and human hair differences. The coating of animal hair insulates just like human hair, but it also provides protection from rain. The growth pattern of hair for animals is more synchronized (or growing together), while human hairs tend to grow independently. Humans get their hair cut to their individual desires, while animal hair grows to a certain point and sheds (falls out) at certain times during the year (i.e., shedding often occurs when the coat is too heavy for the weather conditions related to the season) to be replaced by new hair when needed. Human hair is generally the same texture, but animals usually have two textures: there is a coarser top layer of hair and a finer layer (called under fur). These different textures help to insulate the animals. Another feature of hair on mammals is that sometimes their hair color blends with their surroundings, which provides protection against most predators.

Little Lion Experiment
As we have just learned, hair serves the purpose of body insulation and protection from other outside elements for both humans and mammals. This experiment will allow you to determine if the shade of human hair has an effect on its ability to insulate the human body.

You will need: access to dark colored hair and light colored hair (see if you can have the scraps of hair left behind at barber shops or hair salons), a scale (something that can measure in ounces), gloves, an apron or shirt that can get dirty, six paper lunch bags, two thermometers, a heat lamp or constant light source, ruler, stop watch and materials to record your results.

Steps
1) Collect the two different colors of hair from a barber shop (you will need approximately 6 ounces in weight of each color);
2) With gloves and apron on, put 1 ounce of each hair color into two different paper bags (remember to keep the hair colors separate);
3) Label the bags according to the type of hair inside and the weight;
4) Close the bags by folding the top down;
5) Repeat Steps 2-4 but put 2 ounces of each hair color into two more different paper bags;
6) Repeat Step 2-4 but put 3 ounces of each hair color into the last two paper bags;
7) Place the thermometers on a table about 15 inches apart from each other;
8) Put the 1 ounce bag of dark hair on one thermometer, and put the 1 ounce bag of light hair on the other thermometer;
9) Place the heat lamp approximately 10 inches in front of the bags and also try to center the lamp (center the lamp so that the light is evenly hitting both bags of hair);
10) Record the temperature changes every two minutes over a total of 10 minutes (do not leave the experiment while in progress);
11) Repeat Steps 8-10 for the other weights of samples;
12) You may want to repeat the experiment more than once for each weight of hair but that is up to you!

Look at your results. How do the temperatures recorded from under the dark hair samples compare to the temperatures under the light hair samples? Hopefully, your experiment was a success and you determined that the dark hair samples showed the greatest temperatures, whereas the bags containing the light hair showed the lowest temperatures. What does this mean exactly? Similar to light and dark colored clothing, dark hair absorbs heat better than light hair. So on sunny days, dark hair will prevent heat from passing through to your head while light hair will allow more heat to pass through.

How Does Soundproofing Work?

2009-02-15T13:55:00.000-08:00

Charles from Altoona, PA, has an older brother that plays the trumpet. His brother practices the trumpet in the bedroom next to his. He wrote in asking if it was possible to block out the sound so that he does hear the trumpet while he’s in his bedroom. Charles is essentially asking about soundproofing. While he probably won’t be able to block all the sound from his room, Charles can take steps to minimize the sound that he does hear.

Average volumes of people talking, television sounds, and music playing can often be heard through walls easily. This is due to the fact that sound is a series of vibrations that move surrounding particles. The series of vibrations, or sound waves, carries the noise from the noise source across the room to our ears. Since particles are required to carry the vibrations, sound cannot travel in a vacuum. The more densely packed those particles are, the better the sound moves through since the particles don’t have to move the surrounding particles much. When you’re in an open field, though, you would notice that sound will not carry as well since the particles are more spread out. The farther sound waves have to travel from one point to another, the fainter the sound will become. When sound waves collide with a solid surface (e.g., a bedroom wall), there are a few things that can happen. The surface will reflect some of those vibrations back toward the source, it will absorb some of the sound by converting the vibrations into heat energy or it will transmit the vibrations to the other side (i.e., into the bedroom).

There are two main things to consider when soundproofing: noise transmission and noise reception. The sound coming from the trumpet is a noise transmission issue, while the desire to block the sound out is a noise reception issue. Next the source of the noise should be considered: the indoor noise vibrations your body feels are structure-borne noise, while overhearing a conversation is airborne noise. Soundproofing can be achieved by considering space, mass, and dampening. Space increases the amount of air between your ears and the source, which diffuses the noise by taking away the vibration channels. Mass, like a bedroom wall, can act as a sound sponge that soaks in the sound waves. Dampening sound requires specific materials (like insulation) that will convert structure-borne sound waves to heat energy. Dampening can be expensive.

Without having to spend money, one step Charles can take while his brother is practicing the trumpet is to create more distance between himself and his brother. For example, Charles can plan to hang out in the basement or another room in the house that’s far away from his bedroom while his brother is practicing. Or Charles could ask his brother to practice in another room that’s far away from his bedroom.

Little Lion Experiment
You cannot see sound waves in the air, but you can see their effects. This experiment will help you see the effects of sound waves. You will need: 1 large cake or cookie tin, 1 sheet of plastic wrap, 1 long rubber band, 1 baking tray, 1 wooden spoon, and some fine sand.
Steps: 1) Make a drum by stretching a piece of plastic film over a large round tin; 2) Stretch the rubber band around the tin to hold the plastic taut; 3) Sprinkle a teaspoon of sand on to the top of the plastic drumskin; and 4) Hold a baking tray above your drum, and hit it sharply with a wooden spoon.

What did you observe? What do you think caused the sand to dance up and down on the drumskin? When you struck the baking tray, the metal continued to vibrate for a fraction of a second afterward. As it vibrated, the air around is also vibrated. These little vibrations in the air, the sound waves, quickly work their way out through the air in all directions. When the sound waves hit the drumskin, the drumskin is vibrated too, which causes the sand to dance up and down on the drumskin. The sound waves that reach your ear make you hear the bang.

Heat Energy Movement and Heat Loss

2009-01-15T13:54:00.000-08:00

Some of you from the Altoona area had recently read about why it feels colder on a windy day than on a day without wind. A few months ago, we had also discussed how it feels warmer on a cloudy day. So what is the science behind these questions, both of which seem to involve heat. It has a lot to do with the way heat moves from place to place, or as scientists call it – heat transfer. One of the basic facts in nature is that heat (which is a form of energy) always moves from a hotter object towards a colder object.

Heat can move in several ways from one place to another. Let us think about the different ways now. Do you know that when you touch a cold wall or a window, your warm hand is actually losing heat to the window glass? This form of heat movement is called conduction. This is the same manner heat moves from the stovetop to the kettle or to a soup pot. Conduction is heat movement by contact. Here the hot body has to touch the cold body for heat transfer by conduction.

But remember the cold wind story, there the heat is moved away from you by convection. Here there is usually a fluid medium, it can be air or water usually which carries the heat away from the hotter body. This is the same way how heat comes into your room through baseboard heaters when hot air is blown into the room. Convection involves another medium, usually air or water, transferring the heat. When cold air leaks into a house, it is convection which is to blame for our heat loss.

A third form of heat transfer, which does not require any medium or contact to occur, is radiation. Here the heat energy travels in the form of waves which can go through even vacuum. This is how the heat energy comes to earth from the sun, across millions of miles in the space. This is also how we lose heat from a closed car in winter, when it is left parked overnight. On a windy day, the wind can add to the loss of heat by taking heat away from the glass surface of windows and the body of the car. Radiation is also why we like to open our curtains on a sunny day in winter, to let warmth in through the glass windows.

One of the best examples of a man made object that tries to prevent heat loss is the thermos flask. If you ever get a chance to see one, you should examine it closely. One of the big benefits of a thermos flask is that it keeps colds things cold or hot things hot. You can read more about it at: http://home.howstuffworks.com/thermos.htm . Also look up the words thermal insulation on the internet and find out what it means.

Little Lion Experiment
We will learn how different forms of heat transfer take place. Caution: We will NOT be using any kind of stove or electric heaters to do these experiments. We will be using hot water from the tap in the house to provide heat to some cold objects. But even with this you need to be extra careful not to spill any on yourself or get scalded. Be very careful and use only small amounts in small mugs. These experiments can all get pretty messy, so do NOT attempt them on carpeted floors at all. Also it is advised to not do it on a wooden floor either as any spill can be slippery and dangerous. Keep plenty of washcloths or paper towels around to take care of spills.

You will need:
1) Cold water
2) Hot water
3) A coffee mug or a cup to pour with
4) A small bucket or a quart saucepan
5) Aluminum foil
6) Plastic wrap
7) A newspaper
8) Two or three Hershey’s kisses kept in a cold place for an hour (yummy chocolate!)
9) A pencil and a small notepad to make notes.

Conduction Experiment Steps:
1) Keep a piece of aluminum foil (10 inch by 10 inch) larger than your hand over a cold glass window and keep your hand on the foil to feel the temperature.
2) Repeat the same step with a newspaper and also with your bare hand (only for a few seconds). Note the case when it felt coldest.

Radiation Experiment Steps:
1) Fill up hot water in a coffee mug almost till the top. Carefully cover the top with plastic wrap till it is snug and tight, tape the overhanging wrap around the cup if possible.
2) Keep the mug inside a bucket/saucepan.
3) Carefully place an unwrapped Hershey kiss on top of the plastic wrap.
4) After 5 minutes, check the condition of the chocolate, has it slightly melted?
5) Try the same experiment, but instead of the plastic wrap, cover the coffee mug with aluminum foil, making sure that the shinier side of the foil faces the hot water. And use a new chocolate.
6) Try the same experiment with newspaper taped to the top of the mug. Observe if any melting occurs.

Think about how the shiny side of the foil acts as a mirror to the radiation heat and prevents it from coming out of the mug. Final tip: you can probably eat the chocolate from the plastic wrap and the foil experiments, but the chocolate from the newspaper experiment may not be clean. Throw it away. Instead of chocolate you can also use small piece of candles/wax.

How Do Animals Survive the Winter?

2008-12-15T13:52:00.000-08:00

With the winter months upon us, Julia from State College, PA, writes in to ask how animals survive during the colder months of winter. She asks does the cold weather affect them? She is also curious about the food they eat during the winter months.
Some animals hibernate all winter, which is actually just a very deep sleep. This allows the animal to avoid the cold weather without having to move to a warmer climate. Hibernation is a way to conserve energy by slowing down all of the body's processes. The animal's body produces less heat so its body temperature gets colder, and the animal also breathes much more slowly. These two bodily changes, along with the fact that the animal isn't moving, allow it to use up much less energy than it does when it is awake. These animals get ready for winter by eating extra food and storing it as body fat, which is used for energy while hibernating. Some also store food to eat later in the winter. Some animals that hibernate include bears, skunks and chipmunks. Cold-blooded animals like fish, turtles, frogs, and snakes, find shelter in holes or burrows. There they spend the winter inactive, or dormant, which is similar to hibernation.
Other animals stay pretty active during the winter, but they must adapt to the changing weather. Many make changes in their behavior or bodies. For example, animals may grow new, thicker fur in the fall to keep warm. Food is often hard to find in the winter, so the animals must adapt to this as well. Squirrels, mice and beavers, gather extra food in the fall and store it to eat later. Other animals like rabbits and deer, spend the winter months looking for moss, twigs, bark and leaves to eat. Some animals even eat different kinds of foods as the seasons change. For example, the red fox eats fruit and insects in the spring, summer and fall. However, in the winter, the red fox cannot find these foods so it eats small rodents instead. These active winter animals must also stay warm through the cold months. They sometimes find shelter in holes in trees or logs, under rocks or leaves, or even under the ground. Some mice and squirrels even huddle close together to stay warm.
Some birds migrate or travel to other places where the weather is warmer or they can find food. Many birds migrate in the fall. The trip can be dangerous, so the birds often travel in large flocks. Birds can fly very long distance but most birds will migrate shorter distances. Other animals migrate, too, including bats, caribou, elk, and whales.

Little Lion Experiment:
This experiment will allow you to determine how much energy animals are saving while hibernating! You will need ice cubes, a small pot and a thermometer that goes down to 40°F (5°C) or lower. If you don't have a thermometer like that, then put a cup of cold water in the fridge, which is almost exactly the same temperature (41°F) as a deep hibernating animal. Put a cup of warm water on the kitchen table. Let both cups sit for 20 minutes. You will need a pencil and some paper to record your observations.
Put an ice cube into the pot. Put the pot on the stove over low heat (get an adult to help you with this step). The ice cube will begin to melt into water. Keep checking the temperature of the water with your thermometer (or compare it to the refrigerated water) to see how long it takes for the water to reach 41°F. We'll call this the "deep hibernator time." Also note how much longer it takes to heat up to 60°F (the body temperature of an animal that is dormant). We'll call this the "dormant time." If you don't have a thermometer, then you can just wait until the water is almost as warm as the room temperature water. Also record how much more time it takes to warm up to 98.6°F, our body temperature (any household thermometer should be able to detect that temperature). We'll call this the "human time."
The amount of time it takes to reach a given temperature is directly related to the amount of energy (heat) that is needed to warm up the water to that temperature. So, the "deep hibernator time" shows how much energy is needed to go from freezing (which is about how cold it is when the animal is hibernating) to the animal's body temperature. Similarly, the "dormant time" shows how much energy is needed to go from freezing to that animal's body temperature. The "human time" shows how much energy is needed to go from freezing to our body temperature. The difference between the "human time" and one of the other times shows how much energy those animals are saving by only warming their bodies up to 41°F or 60°F instead of normal body temperature.

Why Do Onions Make Us Cry?

2008-11-15T14:36:00.000-08:00

Shanna from Altoona, PA, was helping her big sister prepare dinner one night, and she noticed that her eyes became really irritated when her big sister cut up an onion. She wrote in asking: why do onions make us cry? We will explore the answer to that question but we will also explore some methods that might minimize the eye irritation. Many people enjoy the taste of onions in their meals. In fact, the average American eats about 20 pounds of onions each year. Onions are healthy components of the human diet because they contain vitamins B and C, protein, calcium, and iron. They also contain quercetin (pronounced KWAIR-SUH-TEN), which is an antioxidant that works to neutralize harmful substances in our bodies that cause tissue damage and aging. In addition to being full of nutrients, onions are low in fat and sodium. However, if you have ever cut into an onion, it is likely that your eyes filled with tears because they became irritated just like Shanna described. But why does this happen? How can we enjoy the taste and benefits of onions without the tears? When you cut into an onion, an enzyme (a biomolecule that speeds up chemical reactions) is released into the air from the ruptured onion cells. This enzyme converts some of the proteins from the onion into sulfenic acids that then become a gas. These can then come in contact with your eyes. These acids contain sulfur compounds that are common eye irritants. The gas reaches your eyes and reacts with the water that keeps them moist. The eyes become irritated, and your brain reacts by telling your tear ducts to produce more water that helps keep the eyes protected. You may want to rub your eyes to help soothe the irritation, but this will only make the irritation worse since your hands may have onion juices all over them. Some people wear goggles to minimize any irritation produced when cutting onions, but some also try the different methods discussed in the Little Lion Experiment. Give each method a try to figure out which one works best for you so you can enjoy onions without any eye irritation!

Little Lion Experiment:

How can we enjoy the benefits and the great taste of onions without the tears? For this experiment, you will explore some methods that are thought to reduce the unpleasant eye irritation that occurs when cutting into an onion. You will need an adult present to help you with this, especially when cutting the onion. It is preferable to try these methods over 5 different days, but you can try each of these home remedies during the same time. Throughout each of these methods, keep track of whether your eyes were irritated when the onion was cut and try to determine which method works best for you.

Items Needed

5 small onions with the outer layers peeled away
1 lemon slice
Slice of bread
Sugar
Bowl of water
Access to a refrigerator
Knife

Procedures

Method 1: Put one onion into the refrigerator. After 30 minutes, take it out and cut the onion.
Method 2: Put one onion into a bowl of water so that it is covered in water. Cut the onion while it is submerged in the water.
Method 3: Put a lemon slice in your mouth. Then cut the onion (keeping your mouth open)
Method 4: Put a bread slice in your mouth. Then cut the onion (keeping your mouth open).
Method 5: Put some sugar in your mouth. Then cut the onion (keeping your mouth open with the sugar on your tongue)

Questions:

Did any of these methods work to keep your eyes from being irritated? If so, which ones worked the best? Having the onion chilling in the refrigerator before cutting it, like in Method 1, is supposed to slow the release of the irritating gases. Keeping the onion under water while cutting it, like in Method 2, is supposed to keep the gases from even reaching your eyes. Keeping the sugar, bread, or lemon slice in your mouth while cutting the onion, like in Methods 3-5, is supposed to keep the gases from ever reaching your eyes since the food will absorb the gases. Try to remember these different methods each time you help out with the cooking at home. And remember to wash your hands after handling an onion since they will be coated in the onion's eye irritating compounds.

How Does Temperature Affect the Cleaning Ability of Soap?

2008-10-15T14:35:00.000-07:00

James from Altoona, PA, was helping his older brother wash some dishes in their kitchen sink recently, and he noticed that the dish detergent seemed to rinse off the dishes better with cold water than with hot water. He also observed that the hot water helped make the dish detergent foam more (i.e., produce more soap suds). He wrote in asking: how does the temperature of water affect the cleaning ability of soap? The use of soaps and detergents is part of everyday life (at least it should be!) so let's first discuss what soap is and how it works. You have probably heard the terms soap and detergent used to describe the various products that are used to clean clothes, dishes, hands, cars, or pretty much anything that needs cleaning. While they are very similar, they are slightly different. A detergent is a substance that cleans dirty or soiled surfaces. It is usually made from synthetic ingredients, which means the ingredients are not naturally occurring and are maufactured from different chemicals. Soap is a type of detergent and is usually produced from natural ingredients. Just from looking around your home, you probably have noticed that soaps and detergents are produced in many different physical forms - for example, there are bars, flakes, pellets, liquids and even tablets! Detergents and soaps contain a basic cleaning agent called a surfactant, which stands for surface active agent. Surfactants consist of molecules that attach themselves to the dirt particles of the dirty material that is being cleaned. The dirt particles are pulled out of the dirty material and are then held in the wash water until they are rinsed away. Most detergents contain a synthetic surfactant in addition to other chemicals that are added to improve the detergent's cleaning ability. Other ingredients that are added to detergents include perfumes, coloring agents and germ-killing or antibacterial agents. When it comes to temperature, hot or cold water is acceptable when cleaning with soap. The most important part of cleaning is using the soap or detergent! You need something that will pull the dirt particles from the dirty areas. Water alone will work OK, but water with soap will work even better.

Little Lion Experiment:

Like James above, you may notice that more soap suds are produced when using hot water. The reasoning for this begins with the fact that warmer water evaporates faster than cold water (the warmer water changes from a liquid to a gas faster than cold water). Soap suds or bubbles are formed more easily when the warmer water is evaporating. Colder water evaporates slower so it is harder to make soap suds. With this information, do you think bubbles will last longer in hot or cold water? This experiment will help you determine the answer!

Items Needed

Two large bowls (or tubs)
Rubber gloves
Tablespoon measuring spoon
Access to cold and hot water (from your faucet is OK)
Stop watch
Some type of soap (you can use dish detergent, laundry detergent, hand soap, etc.)

Procedures

Fill one bowl with warm water and the other bowl with cold water.
With the gloves on, add one tablespoon of your soap to each bowl.
Use the tablespoon to mix the soap into each bowl for 30 seconds.
After mixing, start the stop watch and observe how long the bubbles remain in each bowl. Did the bubbles last longer in the warmer water or the cold water? Why do you think this is so? With the faster evaporation of the warm water, the bubbles may form more quickly than the cold water but that also means that they will disappear sooner too. The slower evaporation of water means that the bubbles may take longer to form but they will also last longer once formed.

What is in the Air We Breathe?

2008-09-15T14:34:00.000-07:00

Laura from Hollidaysburg, PA, was recently helping her parents clean her home, and she noticed how much dust there was on the tables, in the air, and coming from the couches! She wrote in asking: Where does dust come from and what happens to it when we breathe it in? About 21% of the air we breathe is actually oxygen, while the remaining air consists of other gases (e.g., nitrogen, argon, carbon dioxide). However, the air also consists of dust, tiny animals, and other stuff! Dust is defined as dry, solid particles that are less than 0.0625 millimeter in diameter, which is smaller than all grains of sand! Most dust is composed of mineral matter that originated from bare soil, plowed fields, river flood plains, and floors of desert basins. Dust also comes from ocean spray, smoke and ash produced by fires, decaying organic materials, and volcanic eruptions. The wind actually lifts up the dust particles and easily carries them long distances around the earth! The dust in your home can also be made up of dust, pollen, mold, sand, skin flakes, and pet dandruff. These air particles are actually the most common causes of allergies or asthma. Humans and animals can also act as carriers of dust and air particles because the air particles can cling to their skin or clothes. When you breathe in, you are also breathing in dust or air particles. Some of these air particles will get caught in your nose hairs, some will get caught in mucus in your airways, and some will make it into your lungs. However, don't worry too much about this, because most of what you breathe in will cling to the hairs on the inside of your nose. These hairs act as a filter, which works to trap the inhaled air particles inside your nose to keep them from traveling into your respiratory system. The hairs usually trap particles that are less than 5 nanometers in size (that is approximately 0.000005 mm!). Aside from the many nuisances of dust around your home, dust actually contributes to some beautiful sunsets and sunrises. That's right, dust is what makes sunsets and sunrises so pretty! The intense red and orange colors of the sky at sunset and sunrise are mainly caused by the scattering, or reflection, of sunlight off air and dust particles. So the next time you are cleaning your house or enjoying a beautiful sunset or sunrise, think of the dust that is contributing to these everyday events.

Little Lion Experiment:

This experiment will allow you to observe the types of air particles you breathe regularly.

Items Needed

6 index cards
Scissors
A pen
6 pieces of string
tape (scotch, masking, duct, or packing tape is good)
A magnifying glass
A ruler

Procedures

Cut squares into the center of each index card. Try to make all the squares the same size (e.g., about 2'' by 3'').
Choose 6 locations within your home that you want to hang the air particle collectors. Some places to hang your air particle collector include: above your bed, on the inside or outside of a window, near a heating vent or air conditioner, above the cooking stove, on a wall near the floor or ceiling, on your main entry door, and under a tree.
Write down the locations on the index cards so that each index card has a different location on it
Write the starting date on each index card
Cover the window on the index card with the tape so that the stick side up or out.
Attach string to each index card, and then hang the cards at the appropriate locations.
Wait a few days and then take the index cards down without touching the tape. Make sure to note the date. Which location had the most air particles collected? Were these locations inside or outside? Why do you think this is so? Think about where air is moving, and where the air particles could be coming from. Use your magnifying glass to examine the air particles up close. Can you recognize any common air particles?

Why Do We Get Sunburns?

2008-08-15T14:33:00.000-07:00

Have you ever forgotten to put on sunscreen, then regretted it the next day? Many of us know what sunburns look like, but do you know why we get them? Let's start with some background information on how our skin responds to light. Cells called melanocytes in the inner part of your skin produce the pigment melanin, which is what gives color to our skin. Believe it or not, we have about 1000 to over 2000 of these cells per square millimeter of skin! If you have dark skin, that means that your melanocytes are programmed to make a lot of melanin all the time. If you have lighter skin, then you have the same number of melanocytes, but they don't produce as much melanin. If you are albino, then your melanocytes cannot do their job because they are lacking an enzyme (a piece of cellular machinery) which is needed to make melanin. On most days, we do not get exposed to enough sunlight to cause us to develop a suntan. However, a nice day spent at the beach is much different. The darker your skin is, the more light you can withstand without having to boost your melanin production. When your body senses that you need more melanin to protect you against harmful UV rays (UV stands for ultraviolet), your melanocytes kick into high gear and you get a suntan. However, if you stay outside for too long, especially without sunscreen, then your body can't make melanin fast enough to keep up with the amount of UV exposure. This is what causes a sunburn. A sunburn can be thought of as a "clean-up crew" of various blood cells being sent to repair the damaged area. This increased blood flow is what causes sunburns to appear red and feel warm to the touch. Starting to sound a bit like a sunburn? There's one thing missing: why does sunburned skin tend to peel? Your body does its best to repair the UV damage, but if the damage is too great, then the unrepaired cells will simply shed or flake off to make room for new healthy cells to replace them, which allows the sunburn to heal. You may have heard about the relationship between sunburns and skin cancer. Even though the "clean-up crew" and the skin cells themselves usually undo the harmful effects of UV, they may not always do a perfect job. This would allow damaged cells to stay in the skin. Most sunburns will not lead to cancer, but a tiny fraction of them can if they damage a cell's ability to stop dividing. This is why it is so important to wear sunscreen in order to avoid over-exposure to UV light. There are two types of sunscreens: those that reflect UV light (like tiny mirrors) and those that absorb it like melanin does. Everyone gains extra protection from wearing sunscreen, but if you are fair-skinned or albino, it is especially important that you wear it. Remember to put it on around 30 minutes before you go outside so that it has time to stick to your skin. Otherwise, it will rub off on the grass or wash off in the water. [Safety note: some people (especially those with sensitive skin) have allergies to PABA, a chemical in some sunscreens. So if you have sensitive skin, you may want to consider buying a PABA-free sunscreen]. For more information, visit http://travel.howstuffworks.com/sunscreen.htm

Little Lion Experiment:

While UV light is harmful in some respects; we need it to stay healthy! This is because our bodies need about 10 to 15 minutes of daily UV exposure to make vitamin D. In fact, many reactions are activated by light (various kinds of light, not just UV). To see how important light is for living things to survive, obtain two small planter pots. Plant about 5 evenly-spaced seeds in each pot. If you cannot purchase seeds at your local hardware or gardening store, you could use seeds from a fresh tomato. Place one pot in front of a sunny window and place the other pot in a dark area (a cabinet would do, with your parents' permission). Remember to water the plants every few days (specific instructions can be found on the seed packet). Check on the plants over the next couple of weeks to compare the seedlings in the light versus those in the dark.

How Does a Pencil Eraser Work?

2008-07-15T14:32:00.000-07:00

The pencil eraser works based on the friction developed between the eraser and the paper. Friction is what causes your hands to heat up when you rub them together. When you rub two objects the roughness of their surfaces contact each other and rub against each other causing friction. A simple pencil is made of a combination of wood and finely ground graphite and clay, mixed with water and pressed together at high temperatures into thin sticks or rods. Graphite is a mineral composed of an element called carbon, and it is black in color. There are also mechanical pencils that need rods of graphite to function like a pencil. You may have heard that pencils are made of lead, but that is actually a misunderstanding that is based on the initial thoughts of those that first discovered graphite - they believed it to be lead, which was not the case at all. However, many still refer to graphite in pencils as lead. Graphite particles are arranged in layers or sheets. A pencil mark consists of graphite particles that have peeled off from the pencil point onto the paper. These particles have an angular, gritty look to them when viewed under a microscope. When the pencil is used on a sheet of paper, the graphite particles lie slightly below the surface of the paper, interlocked between its fibers. A single rub using an eraser sufficiently soft to reach between the fibers will pick up most of the graphite particles. Looking at the eraser you can see undamaged graphite pieces sticking to the surface. An effective erasing material scratches the paper surface, producing the familiar small spindles of rubber or eraser material, which wrap up the graphite particles. When you look at these under an optical microscope at 200 times magnification (200x), these look like roly-poly puddings studded with graphite raisins.

Little Lion Experiment:

Erasers come in a variety of colors: white, pink and gray are some of them. Sometimes the color difference is because of a dye or because the eraser is made of a different type of rubber. Go around your house and see how many types of different erasers and pencils you have. For example, compare number 2 pencils with a number 3 pencil. Also, if someone in your home has a mechanical pencil, you can purchase different types of pencil leads (like hard black or soft) or they might have different leads you can use. The bright-colored erasers (like purple and yellow) are usually white erasers in disguise! You can also use erasable pen as a pencil type. See which one of these works best with different types of pencils and ink. Can you erase the ink with a pink or white eraser? Is there one eraser that works for all lead types? Knowing what you know about how erasers work, why do you think certain erasers do not work with other types of pencil lead and ink?

Why Does Ice Float?

2008-06-15T14:31:00.000-07:00

It is almost officially summer! And that means plenty of sunshine and hot temperatures. With all the sun and heat, you will likely be drinking more water to keep hydrated. Most people prefer their water to be "ice cold", which just means there is ice in the glass to keep it cold. But, you may have noticed that ice doesn't just sink to the bottom of the glass - have you ever wondered why? This month we will explore that very question! The meaning behind this mystery lies in the different properties of solid and liquid water. Nearly every solid, if placed in its liquid form, will sink to the bottom. Luckily for us, the properties of water are different. Unlike most other substances on Earth, the solid form of water floats on the liquid form. This is caused by the change in density, which is defined as the amount of mass in a volume. With the exception of water, most substances on Earth become denser as they become colder. The solid ice will float because its density is lower than that of water. It is about 9% less dense than water. The denser water sinks to the bottom forcing the less dense ice to the surface. What makes water molecules different from other molecules is that they attract each other in an organized fashion. As the water cools, the molecules begin to bind to each other, forming a hexagonal pattern (shape that has six sides). Water is at its densest point at 4 degrees C. After that point, the water molecules move very slowly and attract to each other. In most substances, the molecules are more tightly packed together in solid form. But in ice, the hexagonal pattern of the attracting water molecules leaves empty spaces. This is why water expands when making ice cubes. The empty space between the hexagonal shapes makes the solid form less dense than the liquid form so that it floats to the top. Thanks to this oddity of physics, the water in our oceans and seas remain in liquid state. If the solid form of ice happened to be denser than water, the ice would sink to the bottom. If this happened, the ice on the bottom would begin to freeze up toward the surface. Eventually, nearly all the water on Earth would become solid ice and never melt. Luckily, ice floats and remains on the surface so that the water underneath remains in liquid form.

Little Lion Experiment:

This experiment will demonstrate that ice does float in most liquids, but you will also test other solid materials to see if they float, too.

Items Needed

4 ice cubes
4 small rocks
4 small magnets
4 quarters
4 glasses
4 different liquids (e.g., water, soda pop, salt water, and milk)

Procedures

Put each liquid in its own glass.
Drop one of each solid material (i.e., ice cube, small rock, small magnet, quarter) into each glass.
Observe what happens. Did any of the materials sink to the bottom or float to the top of all the glasses? Did some sink to the bottom of one glass but float to the top of another glass? What can you conclude about the solid materials? What can you conclude about different liquids used? Keep trying different solid materials and different liquids to see how they compare!

What Are Allergies?

2008-05-15T14:30:00.000-07:00

A-choo! With all the flowers blooming, it is no wonder that hay fever is upon us - that is, it is allergy season! Kaylee from Altoona, PA, who suffers from seasonal allergies writes in to ask about allergies. We are all familiar with the coughing and sneezing, but what exactly are allergies and what causes them? Every day, our bodies are in constant contact with potential threats. These include pathogens (harmful microorganisms), pollution, and a host of other dangers. However, most of the time, we aren't even aware that anything nasty has entered our bodies. How are we able to combat these invaders so effectively? We have our immune system to thank. Immune cells called lymphocytes (pronounced lim-fo-sites) patrol all parts of the body looking for foreign molecules and microorganisms (tiny living things, like bacteria). Each lymphocyte is programmed to recognize a specific pathogen. Anything which is not part of our body is classified as "non-self" while every one of our own cells is termed "self." In short, the role of the immune system is to attack and destroy any cells it finds that are "non-self." We also have sensors in our bodies which can detect the presence of harmful chemicals. Have you ever walked by a car and coughed or sneezed as you smelled the exhaust? This is because you have sensors in your nose, throat, and lungs that tell your brain that you have inhaled dangerous fumes, which you need to get rid of right away. So, your body sends the signal to cough and sneeze until you push out all of the fumes. This signal is sent by a chemical messenger called histamine. If you have allergies, or know someone who does, then you might agree that the symptoms of allergies are kind of like a huge overreaction to the car fumes, except without the car! People with allergies react as if they have inhaled something toxic when in fact they have just inhaled normal everyday things like pollen and dust that are not harmful (these everyday substances are called allergens). This occurs because some of their lymphocytes are programmed to recognize the allergen as a harmful substance even though it is not. So, when the lymphocytes find an allergen floating around in your body, they trigger histamine to be released which causes the common allergic symptoms such as watery eyes, runny nose, sneezing and coughing (these are all ways to flush out the allergen). Histamine also triggers local swelling near the pathogen or allergen, and so it can cause narrowing of the airways (nose and throat) when you inhale pollen or dust in order to prevent more of the allergen from entering the lungs. Unfortunately, that makes it harder for the person to breathe. Here's an interesting fact: histamine is also responsible for asthma - can you see the connection? So how can we treat allergies? The primary method to prevent allergic symptoms is to treat the person with antihistamines, which have been used since the 1930s to control allergies. The medicine does not affect the lymphocytes, but rather it just prevents histamine from triggering its bothersome symptoms.

Little Lion Experiment:

This experiment will demonstrate how allergens or pathogens may stick to the lining of your nose or throat to cause sneezing and coughing.

Items Needed

An empty toilet paper roll
Running water from your sink
Black Pepper
Salt
Confectioner's Sugar
Jimmies or sprinkles

Procedures

Run water over the inner surface of the roll until it is wet but not soggy.
Hold the tube sideways in one hand over a sink (so as not to make a mess) and carefully place the pepper on the inside of the tube
Rotate the tube until it is coated with the pepper.
Repeat steps 2 and 3 with the salt, sugar, and jimmies

Did all of the substance stick? If the substance does not stick, then that is a pretty good indication that it is large enough that it would not stick to the lining of your nose or throat. If it sticks, then it is probably something that would get trapped in your airways if you were to inhale it. Now, slowly turn the tube until it is vertical. To simulate coughing, quickly shake the tube or bang it against the inside of your sink. See which kinds of substances come out the most easily. To simulate sneezing, blow air through the tube and see what comes out in your sink. The body also uses mucus in your airways to help carry foreign molecules out (like the sea carries shells to the shore). Pour a small amount of oil into the tube and see if it takes out some of the remaining particles.

What is the Water Cycle?

2008-04-15T14:30:00.000-07:00

Cole from State College, PA, wrote in to ask if the Spring-time saying “April showers bring May flowers” is true. The saying points to the theory that the large amount of rain observed at this time of year is thought to assist in the growth of plants and flowers that generally bloom in May. However, flowers actually bloom at different times during the year depending on their location, so timing of rainfall that aids in the health and growth of flowers is different depending on that location. Too much rain can also negatively affect the plants by making them more susceptible to diseases or killing the roots. This question brings up another good question, though - where do “April showers” come from? To answer that, we’ll need to learn about the water cycle.

The water cycle is a term used to describe the continuous movement of water in and around the Earth. About 70% of our Earth is covered by water, which amounts to approximately 333 million cubic miles! So that’s a lot of water in constant operation – but how is it in a constant cycle?

Two major components of the water cycle are evaporation and condensation. Evaporation occurs when a substance goes from the liquid to the gaseous state, and condensation occurs when a substance goes from a gaseous to a liquid state. These processes happen on Earth with the help of the sun. The sun heats the surface of water causing it to evaporate into water vapor (gaseous water), which rises into the atmosphere. This water vapor then cools and becomes clouds, which eventually condense into water droplets. Depending on the temperature of the atmosphere, the water then precipitates (falls back to the Earth’s surface) as rain, sleet, hail or snow. Some of this precipitation falls on trees or other plants and can evaporate again into the atmosphere. The precipitation can also continue to the ground, and now the water is considered runoff water. This runoff water can then get into the ground and accumulate where it is eventually stored in aquifers, which are large, natural storage tanks of groundwater that can be used later if needed. The runoff water can also form or add to lakes and streams, which can also then freeze into snow caps or glaciers. Water that falls to the ground and stays in the soil ends up evaporating and returning back to the atmosphere – you can see how this is a continuous cycle! The water in aquifers, though, can accumulate there for thousands of years. Aquifers are actually our major sources of drinking water.

So consider the long journey water has taken the next time it rains, snows, hails or sleets. Maybe it end up as your drinking water or maybe it will end up in your local water reservoirs. Perhaps, it will just evaporate back into the atmosphere to come back to the Earth’s surface as rain another day.

Little Lion Experiment
This experiment will allow you to create a small-scale model of the water cycle using common items found around your house. You will need: plastic wrap, a large bowl (preferably one that is clear), a weight (a paperweight will work), small container (a clean, empty yogurt cup works well), a rubberband or piece of string, tap water, paper and pencil. You will also need access to sunlight.

Steps: 1) Place the small container in the middle of the large, clear bowl so the opening of the small container is up. 2) Fill the bowl with some water (at most half full) but be careful not to fill the small container inside. 3) Cover the bowl with plastic wrap. 4) Fasten the plastic wrap around the bowl’s rim with the rubberband or string. 5) Put a weight on top of the plastic wrap in the center. 6) Put the demonstration on a window sill or somewhere that it will be in contact with the sun. 7) Record your observations of the experiment every 10 minutes on your paper (you should conduct this experiment for at least an hour).

What did you observe? Hopefully you saw that the heat of the sun evaporates the water, which rises, condenses on the cool plastic, and falls into the small container similar to how rain falls. Now that you know how to make your own model of the water cycle, change some of your materials in the experiment. For example, use salt water instead of tap water. Or, you could use ice water (a mixture of water and ice chips) instead of tap water. Were you still able to observe the water cycle?

Why Do Our Ears Pop on an Airplane?

2008-03-15T14:29:00.000-07:00

Jeff from State College, PA, is going to Florida for his Spring Break and will be taking an airplane to get there so he asks, why do our ears pop when we fly?

The human ear consists of the outer ear, middle ear, and inner ear which is fairly deep inside of your head. The middle ear is separated from the outer ear by the eardrum allowing the air trapped inside the middle ear not to come in contact with the air outside of your head. When you experience a change in air pressure by getting closer to or further from the ground, your ears will occasionally "pop" to adjust the pressure of the air that is caught in your middle ear so that it matches the air pressure outside of your head. This is done by quickly opening the Eustachian tubes, which connect the middle ear to the back of the nose, in order to let air rush in or out of the middle ear as needed.

The most common place for someone's ears to "pop" is on an airplane, but it can also happen with smaller changes in altitude (the height above the Earth's surface), like when you are driving up or down a mountain. The air closer to sea level is at a higher pressure since it is being compressed by the weight of all of the air above it. As you climb to higher and higher altitudes, the air pressure decreases. Some people may find the popping of their ears to be annoying, but if your body didn't do this, then the pressure on one side of the eardrum would be higher than on the other side which could bend your eardrum slightly and compromise your hearing.

If your plane is taking off, then you are going to an area with lower pressure so the high-pressure air in your middle ear will push outwards on the eardrum. When your ears pop, air rushes out. If you are coming in for a landing, then you have low-pressure air in your head (from when you were at a high altitude) and high-pressure air outside pushing inwards on your eardrum. When your ears pop, air rushes in.

One way to make this pressure equalization more comfortable is to do it yourself by swallowing or yawning frequently rather than waiting for your ears to pop by themselves. These methods work because swallowing and yawning cause the Eustachian tubes to open briefly. This is why many people choose to chew gum when their plane is taking off or landing (chewing gum or sucking on a hard candy makes you swallow more than if your mouth were empty).

Little Lion Experiment:

If someone has a blocked or oddly-shaped Eustachian tube, then their ear will fail to pop as their plane is landing. This creates a small vacuum in the middle ear. Fluid then rushes into the middle ear to increase the outward pressure until it equals the inward pressure from the surrounding high-pressure air. This experiment will help you observe the effects of having a blocked Eustachian tube. You will need: a small plastic cup (if possible, use a clear cup), a bowl with a flat bottom, and some water.

Steps

Fill the bowl with about an inch of water.
Turn the empty plastic cup upside-down and squeeze it until it bends inward.
Place the bent cup in the water.
Being careful not to let the lip of the cup rise above the water level, slowly squeeze the creases in the cup outwards so that the cup returns to its original shape.

By doing this, you are creating a small vacuum. So, the pressure inside the cup (which pushes outwards) is lower than the pressure outside of the cup (which pushes inwards), and this pressure difference is what pushes the water from the bowl into the cup until the two pressures are equalized. As a side note, the same principles of air pressure explain how straws, turkey basters and a variety of other objects are able to move liquids against gravity.

What is Cheese?

2008-02-15T14:27:00.000-08:00

Betsy from State College, PA, sent in a question asking why certain types of cheese can be both white and yellow, so this month we will learn about cheese!

Cheese is probably in a lot of your favorite foods especially if you like pizza, lasagna, enchiladas, or macaroni and cheese. Some say that any food tastes better with cheese, but what is cheese? Cheese is essentially a preserved form of milk, which usually comes from cows but can also come from goats or sheep. About 80% of milk in its natural state is water. Cheese is basically formed when the water from milk is removed and the curds (the remaining solids) are compressed, which means the solids are squeezed or pressed together. However, cheese makers can do many different things to the curds to enhance the flavor and color to make the various kinds of cheese that you are used to. Think about how many types of cheese you already know about. It’s no wonder that cheese can be classified according to its age, country of origin, fat content, dairy content, texture, manufacturing methods, and more.

Fresh cheeses like cream cheese, ricotta, cottage cheese, and mozzarella, are the most basic cheeses because they are uncooked, unaged and sometimes still contain whey (the liquid part of milk). These cheeses must be eaten soon after they are made because they spoil quickly. Soft-ripened cheese like Brie is created from the introduction of a mold during the ripening process, or aging process. Mold is a form of fungus, which gives the cheese more flavor. Blue-veined cheeses are similar and develop blue or green streaks of harmless, flavor-producing mold throughout the interior. Washed-rind cheeses like Limburger are washed in a liquid (i.e., salted water, wine, or beer) that encourages the growth of bacteria and mold during the ripening phase, which gives the cheese a very strong smell and taste. Cheddar is an uncooked, pressed cheese, which means its curds have not been heated and the cheese has been pressed to give it a very compact, dense texture and flavor. Cooked, pressed cheese like Parmigiano-Reggiano and Provolone has its curds heated before being pressed. Processed cheese (like American, Velveeta, and spray cheese) is not technically a cheese but is actually a byproduct of the cheesemaking process. Byproducts are products made during the manufacture of something else. Processed cheese can be made with scraps of cheese but can also include whey, cream, water, dyes, gums and other ingredients. This type of cheese lasts a long time and melts easily.

So, how can some cheeses, like cheddar, be both yellow and white colors even though they are the same type of cheese? Cheese used to be different shades of white, yellow or orange, depending on when it was made during the year and also what the cows had eaten. For instance, in the spring/summer, cows eat fresh grass and other plants that contain beta-carotene and vitamin D which results in cheese that is yellow in color. In the winter, cows eat hay, which caused cheese to be pale in color. Cheese that is yellow in color is generally more desirable, so cheesemakers now dye their cheese.

Little Lion Experiment
This experiment will expose you to the many different kinds of cheese available at your grocery store or even in your own refrigerator! Much like there is a vegetable section, most supermarkets will have a section totally devoted to cheese. The next time you go to the supermarket with your parents, see if you can browse the different kinds of cheeses there. Then ask your parent if you can try 5 of these different cheeses (you will probably have to buy the cheese to taste it). Try to pick at least one kind of cheese that is two different colors (for example, yellow cheddar and white cheddar). Taste each kind of cheese and decide if you think the cheese is soft-ripened, blue-veined, washed-rind, uncooked-pressed, cooked-pressed, or processed. Try to pick cheese that you know you enjoy and also pick some cheese that you have never had. Check your refrigerator before you go to the store, too, to see what kinds of cheese you might already have! For the cheese that is two different colors, decide if you think each cheese sample tastes the same or different. Do you think one of those cheeses was dyed? Tasting the different kinds of cheese will allow you to identify the kinds of cheese that you like and dislike. You will also be able to explain to others why the cheeses can taste so different!

Science Lions is a Penn State University student volunteer organization dedicated to fostering science and engineering interest in students in kindergarten through grade 12. To learn more about the Science Lions and to submit a question for Ask Science Lions, visit http://www.clubs.psu.edu/up/sciencelions/.

How Do Thermometers Work?

2008-01-15T14:27:00.000-08:00

You may not realize it, but there are many different types of thermometers around you. A thermometer detects or measures a change in temperature. Some thermometers are better at accurately measuring the temperature of something - these would be used for measuring your body temperature to see if you had a fever, measuring the temperature outside, or measuring the temperature of meat to make sure it is cooked thoroughly. Others are better at controlling the temperature at a set level - these would be utilized in refrigerators, ovens, and furnaces. However, both types of thermometers work differently.

The bulb thermometer is the common glass thermometer that you may be most familiar with. Perhaps you were sick and used this type of thermometer to see if you had a fever. It contains a fluid, which in principle changes its volume relative to its temperature - this simply means that the fluid will occupy less space when it is cold and it will occupy more space when it is warm. So when the thermometer is in contact with something warm, the fluid will expand and rise up the glass column where the corresponding temperature can be read. Mercury used to be the fluid of choice for these types of thermometers, but nowadays most bulb thermometers use a non-mercury fluid since mercury is toxic

A bimetallic strip thermometer is good at controlling temperature and like its name suggests is made of two different metals (usually steel and copper). The two metals are bonded together and either left as a strip or coiled. The metals expand at different rates as they are heated. The different expansions cause the flat strip to bend one way if heated or bend the opposite direction if cooled below its normal temperature. When the strip is bent, it can make contact so that a current related to the temperature can flow. The temperature can be controlled by adjusting the size of the gap between the strip and the contact.

These types of thermometers work very differently but are equally important. Try to identify which type of thermometer is used in the many different devices that you encounter in your everyday life that utilize temperature to function.

Little Lion Experiment:

In this experiment you will make a simple bulb thermometer, which will mimic how a typical bulb thermometer works.

Items Needed

Clear, plastic bottle (water bottle would work!)
Cold water
Rubbing alcohol (make sure to get help from an adult with this!)
Clear, plastic drinking straw
Modeling clay or silly putty
Food coloring

Procedures

Fill the bottle with equal parts water and rubbing alcohol until the bottle is 25% full.
Add a few drops of food coloring.
Put the straw in the bottle, but don't let it touch the bottom.
Use the modeling clay to seal the neck of the bottle so the straw stays in place (i.e., keeping the straw from touching the bottom of the bottle).
Hold your hands on the bottom of the bottle.

What happened? Did the liquid mixture move up the straw? Why do you think this happened? When you put your hands on the bottle, you heated up the water. As we discussed above, liquid mixtures will generally expand when they are heated. So as your hands heated the water/alcohol mixture, the mixture expanded and could no longer fit in the bottom of the bottle causing it to move up the through the straw. Try sitting the bottle in the sun. Did this cause the mixture to move up the straw more?

What Happens to Our Trash?

2007-12-15T14:25:00.000-08:00

You probably take the trash out at least once a week. If you live in a house, then you most likely put it in a trash can, which you place at the curb in front of your house on trash day. Then once a week a large garbage truck will stop at your house and empty your trash into the truck. If you live in an apartment or condominium, then you probably put your trash into a larger metal bin that holds other people's trash also. Then, just like if you lived in a house, a garbage truck comes and empties all the trash into it and takes the trash away. This routine takes place everyday in the United States, but what ultimately happens to your trash?

Some of your trash can be recycled including plastic bottles, aluminum soda cans, glass bottles, newspaper, and more! These recyclable items are cleaned, processed, and eventually manufactured into new (and sometimes different) products that can be sold for a profit. For example, plastic bottles can be recycled and made into fleece clothing! In 2006, the Environmental Protection Agency estimated that over 251 million tons of solid waste was generated in the USA by all the residents, businesses, and institutions. That same year, over 82 million tons of trash was recycled!

Most of your trash will go to a landfill, which is a carefully designed structure that is built into or on top of the ground. Trash is isolated from the surrounding environment (e.g., groundwater, air, rain) through the use of both a bottom liner (usually made of clay or plastic) and a daily covering of soil on top of the buried trash. Keeping the trash isolated like this does not allow it to decompose (i.e., breakdown or degrade into smaller pieces) like it would if it was present in the environment as litter or in a compost pile. The purpose of a compost pile is to bury the trash in a way that it decomposes quickly through biodegradation. Some common items that we use everyday are biodegradable, which means these items can break down safely, and relatively quickly, by biological means into the raw materials of nature and disappear into the environment.

However, not all kinds of trash can break down easily and may remain unchanged in the environment for over 100 years or even forever! You will investigate this during the following experiment. With this in mind, we must be careful not to be wasteful since much of our trash may remain as trash forever. We should also strive to recycle as many relevant items (like paper, cans, glass bottles, etc.) as we can.

Little Lion Experiment:

In this experiment, you will determine if some of the common items that you throw away are biodegradable.

Items Needed

5 plastic quart-sized bags (preferably with a zipper closure)
compost or garden soil (the soil can be from your actual garden or it can be obtained from a local recycling center or store)
water
5 straws
a permanent marker
a variety of 5 materials to test for biodegradability. Some materials you could use include chewing gum with packaging, toilet and facial tissue, paper bags, newspaper, styrofoam, aluminum foil, leaves, grass clippings, cotton rags, banana peel; do not use animal products).

Procedures

Fill each of the plastic bags with three cups of uniformly moistened soil.
Thoroughly wet each material to be tested and blot away any excess water from the surface.
Place each of the testing materials into its own plastic bag. Make sure that the item is in good contact with the soil and can be easily observed through the bag.
Insert one plastic straw at one edge of each bag, and zip the bag closed so that the straw sticks out of one side of the bag. This will allow some air into the bag. Be careful not to insert the end of the straw into the soil.
Use the permanent marker to label each bag with the date, the material being tested, and soil type.
Use the permanent marker to label each bag with the date, the material being tested, and soil type.
Record your daily and weekly observations of each material for at least 1 month in a journal. You can continue the experiment for as long as you like.

Did any of the materials degrade after a week? After a month? You will find that some of the materials will fully degrade after a few weeks, while some may never degrade fully unless you continue the experiment for many years - over 100 years in some cases! Check out this website for a table that estimates how much time it takes for some commonly used products to biodegrade when they are in the environment as litter: http://www.worldwise.com/biodegradable.html .

For disposal: Remove the straws from bags and add a chemical disinfectant (e.g., Lysol or Clorox) to the bags before throwing them out for good.

Why Do We Need to Sleep

2007-11-15T14:24:00.000-08:00

What is something that you do that takes up more than a third of your day? Sleep! In fact, the average human spends about one third of their life sleeping! Children in elementary school and grade school need approximately ten to eleven hours of sleep each day. Babies and infants sleep around sixteen to seventeen hours a day. Adults sleep around eight hours a day. But why do we spend so much time sleeping each day when we could be doing other things?

Most kids have a very busy day: you wake up in the morning, go to school, go to sports or dance classes, go to music practice, ride your bike around the neighborhood, and maybe even just run around and play with your friends. By the end of the day, your body gets very tired. Sleeping is a chance for your body to catch up and regain the energy needed to be active again tomorrow. The brain also takes this time to analyze all that happened that day and categorizes it. If you do not get enough sleep, your body will respond by being tired the next day.

If you don't get enough sleep the night before, you might find yourself finding it difficult to take a test or be as active. Scientists have recently found that children who get enough sleep each night have better immune systems. This means that sleeping is healthy for your body and keeps you from getting sick! Sleep is also important for growing children because that is the time when the body rests and repairs itself.

Sleep is a mysterious thing to most people. After all, at night, we just close our eyes, maybe dream a little, and then wake up the next morning! What was our body doing the whole time? First, your brain tells your body to calm down and relax. Next comes light sleep, where you might still be easily woken up. Then comes a deeper sleep called "slow wave," which is harder to be woken up and some people may sleepwalk or sleep-talk at this point. The final stage of sleep is called REM, which stands for Rapid Eye Movement. During this stage, people's eyes move quickly under their eyelids but their bodies are still sleeping and relaxed. Eye movement is an indication of dreaming and REM is the time when people dream. Scientists do not know exactly why we dream but they think it might be the brain trying to sort out what happened during the day. Your dreams might indicate what is worrying you or what you are particularly happy about. We repeat this process of light sleep to REM about every hour and a half until we wake up in the morning.

Now that we learned about the importance of sleep, here are some tips to help you get the sleep you need. Try to go to sleep at the same time each night; this lets your body know what and when to expect to sleep. Avoid foods and sodas with a lot of caffeine and sugar, this can keep you from going to sleep. Finally, Halloween is over and you should not be watching scary TV shows or movies right before going to sleep. This might make it more difficult to fall asleep and it might give you bad dreams at night.

Little Lion Experiment:

Do you think you can see a person dreaming? Maybe you won't be able to see that person's actual dream but you might be able to tell if he or she is dreaming! Remember REM? When there is rapid eye movement while someone is sleeping, he or she is probably dreaming.

Try and get a friend, sibling or parent to close their eyelids and move their eyes around. You should be able to tell that their eyes are moving under their eyelids. Once you are able to tell when somebody's eyes are moving, see if you can catch a person actually dreaming! While a family member is sleeping or taking a nap, quietly watch to see if they have any eye movement. Remember to be very quiet and not wake this person up. If he or she is still in the light sleep stage, you will need to be very very quiet. If you see eye movement, wait until the person wakes up to ask him if he can remember his dream. It's okay if he can't, we don't remember most of our dreams.

Now try this on your pet dog or cat. Do animals dream? If so, what do you think they are dreaming about?

Why Do Leaves Fall From Trees?

2007-10-15T14:23:00.000-07:00

Fall is the season that we get to enjoy the colors of many different types of leaves changing from green to brilliant red, yellow, orange, and/or brown colors. However, the leaves are also undergoing other physical changes besides the changing colors - that is, the leaves begin to fall from different trees and plants. But why do the leaves fall, and why do some plants have leaves that do not fall? We will first talk about the different types of trees that lose or do not lose their leaves. Then we will discuss the reasoning behind how or why the leaves fall off.

There are two different types of trees and plants: deciduous and evergreens. Deciduous trees (like elm or maple trees) grow in temperate climates and usually lose all of their leaves for part of the year. Evergreen trees, like pine or spruce trees, keep their leaves in the fall because they are resistant to water loss and cold temperatures. Deciduous trees generally have broad leaves, while evergreen trees have long, thin needles for leaves. The evergreen needles are coated with wax to keep the water in all year long.

Trees are naturally tough plants - a tree's roots, branches and twigs can tolerate freezing temperatures. However, most trees' leaves cannot withstand really cold temperatures so the tree must shed the leaves at some point during the year in order to survive during the winter. Leaves are made up of cells that are filled with water sap. At the base of each leaf stem on a tree, there is a layer of cells called the abscission or separation layer. During the summer, small tubes in the separation layer carry water into the leaf and food back to the tree. In the fall, this layer swells and makes a cork-like substance that stops the flow of water and food between the leaf and the tree. This cork-like layer is formed when the veins that carry sap into and out of a leaf gradually close, which destroys the tissues that nourish the leaf. These veins close as a result of the days getting shorter during the fall months (i.e., there is less sunlight per day). The separation layer then forms a tear-line, and soon the leaf blows away due to the wind or it falls from its own weight. The tree then seals itself where the leaf detached, which is similar to how our bodies can seal small cuts with scabs, and it is now ready for the winter. An exception to all deciduous trees losing their leaves is the oak tree. Even though oak trees are considered deciduous, some oak leaves remain on the tree through winter because the separation layer never fully detaches the dead oak leaves.

So the next time you are asked to rake the leaves of your front yard, you will understand why they have fallen in the first place!

Little Lion Experiment:

This experiment is more of an observation. It is simple and involves spending time outside looking at trees trying to identify whether the trees you see are deciduous or evergreen trees. The trees can be in your neighborhood, in a nearby forest or park, and/or at your school. You will need an adult to come with you as you look at the different trees. You may also want to take a small bag to collect any leaves that you might want to keep. Take notice of the trees that have already begun to lose some of their leaves compared to those that have not lost many of their leaves yet. Try to visit the same trees a few more times this month to observe the changing leaf colors and the amounts of leaves falling. Did you find any trees that did not lose any leaves? Did you find any trees that did not change colors?

Even though we did not talk about leaves changing color much, here's an online scrapbook that shows what some leaves look like when they change color: http://www.mbgnet.net/sets/temp/leaves/index.htm .

Why do we yawn, and is yawning really contagious?

2007-09-15T14:22:00.000-07:00

You see, hear, read about, or think about someone yawning and now you want to yawn. Everyone yawns - babies, adults, teenagers, even animals! Most people relate yawning with fatigue, boredom, or drowsiness. But sometimes, regardless of how awake or stimulated you are, you can yawn simply because you observed someone else yawning. If this describes you, then you have just caught a yawn.

Yawning is an involuntary action. This means that we yawn without thinking about it, which is similar to when we breathe. The average duration of a yawn is 6 seconds. When we yawn, we open our mouths wide and breathe in deeply to take in as much air as possible. The inhaled air fills our lungs and expands them to capacity. Then some of the air is blown back out.

While there is no proven scientific explanation for why we yawn, there is thought that yawning is like stretching - both yawning and stretching increase blood pressure and heart rate, and they both flex muscles and joints. Evidence for relating yawning to stretching stems from trying to prevent a yawn from occurring. Have you ever felt a yawn coming and tried not to yawn? If so, you probably clenched your jaws shut and found it difficult to stop the yawn. Some researchers also proposed that yawning is used to cool the brain. For instance, people were observed to yawn more often in warm rooms, compared to when they were in colder rooms. Others think that yawning is a means of communication, which has evolved since our ancestors. Yawning could have been used as a signal to the other group members. However, none of these theories have actually been proven making yawning still one of the greatest mysteries.

So, have you yawned at all since you have read this?

Little Lion Experiment:

Although the cause and purpose of yawning is not understood, yawns seem to follow a daily cycle. This means that most people yawn around the same time of day everyday. While the actual times that people yawn can vary depending on the individual, most people tend to yawn soon after waking up and also about an hour before bedtime. This experiment will help you determine your yawning cycle.

Items Needed:

Paper
Pencil
A clock or watch

Steps:

On your piece of paper, write down: a) date, b) day of the week, c) time that you woke up, and d) time that you went to bed.
Below that, record each yawn throughout the day and write down what time the yawns occurred according to your clock or watch. Keep your paper in a handy place so you are able to record each yawn.
Repeat steps 1-2 for 7 days.
At the conclusion of the 7 days, compare the amount of your yawns per day and also what times they occurred throughout the week.

Questions:

Were there days when you yawned more than others?
If so, did you wake up or go to bed at different times than usual?
Did you tend to yawn more soon after waking up and/or just before bedtime?

Another quick experiment involves observing if yawns are contagious. The next time you are with a group of people, take a big yawn (make sure to cover your mouth out of courtesy to others). Did you notice whether anyone else yawned?

How Can You Tell If Something Is An Acid Or A Base?

2007-08-15T14:20:00.000-07:00

You have probably heard the terms acid and base before, but what do they mean? To help explain, we'll first talk about water and the elements that combine to form it. Then we'll talk about the role of pH in acids and bases.

Most acids and bases that we encounter in common use are usually liquid solutions. These solutions are formed from molecules that dissolve in water to give ions. Ions are atoms with an excess or deficiency of electrons, which gives them positive or negative charges. Water is formed from a balance of hydrogen and oxygen ions. Hydrogen has one positive charge, while oxygen has two negative charges. Therefore, two hydrogen ions are needed to balance the oxygen ion so water's overall charge is zero. This is because all matter is fundamentally neutral in charge or strives to become neutral.

Some chemists define acids as substances that can add hydrogen ions to a solution, while bases are substances that can take away hydrogen ions from solution. So, substances that have an excess of hydrogen ions are acidic. Alternatively, substances that are lacking hydrogen ions are basic. Every solution is generally either acidic or basic. Even tap water can be either slightly acidic or basic due to the natural elements like calcium or magnesium that are often naturally found in it.

The pH scale is used to indicate how acidic or basic a solution is compared to a neutral substance like water. The pH scale ranges from 0-14: pure water is has a pH value of 7 (the value for neutral substances), acids have pH values less than 7 (down to 0), and bases have pH values greater than 7 (up to 14). The acidic strength of a solution is higher as the pH value is lesser. Likewise, basic strength of a solution is higher as the pH value gets closer to 14.

But, how do you determine a pH value? A pH indicator is often used to estimate the pH value of a solution. The indicator is typically a chemical that changes color if it comes in contact with an acid or a base. There are many different kinds of chemical pH indicators, but a natural indicator is red cabbage juice. Red cabbage juice changes color when an acid or base is added to it. The juice generally turns dark red when an acid is added, while it usually turns green or yellow when a base is added.

Little Lion Experiment:

Most homes have a variety of items that are acidic or basic. This experiment will allow you to determine if common solutions around your home are acidic or basic using red cabbage juice. You will want to have the help of a parent or guardian throughout this experiment, especially when making the cabbage juice and when testing the items gathered from around your home.

Items Needed:

Stovetop
Head of red cabbage
Water
Pot for boiling water
Ladle
Disposable cups/bowls (plastic may get stained red)

Steps:

Rip or cut the red cabbage into pieces (they should be small enough to fit in the pot).
Add some water to a pot, and begin to boil the water on the stovetop (the amount of water should be similar to the amount used to cook pasta).
Add the shredded cabbage to the boiling water and let it cook for approximately 10 minutes.
After both the water and pot cool down, use the ladle to spoon the liquid only into the bowls. The red cabbage juice is usually violet in color. Now you are ready to test some solutions from around your home to determine if they are acids or bases!

Some items you can test in your cabbage juice include (but are not limited to): orange juice, lemon juice, windex (with ammonia), vinegar, baking soda, soda pop, laundry detergent and antacids (like TUMS or Maalox). You can test any solution in the juice, but the items listed above should give good results! To test a solution, you just add some of the solution to the juice and see what color it changes to.

Questions:

Which of these items were acids or bases?
What different colors did the juice turn in the presence of the acids or bases?
What colors would the juice change to if you first added a solution that was acidic to the juice, and then added a basic solution?
What color would the juice change to if you first added a base to it and then an acid?

What Causes Lightning And Thunder?

2007-07-15T14:19:00.000-07:00

This summer we have already seen several thunderstorms that came upon us suddenly during the day. Along with the sudden rains they also bring with them some grand displays of nature's firepower - lightning and thunder. Have you ever wondered what lightning is all about and why lightning and thunder always come together, or well, almost together? Today, we will learn about all of these.

Lightning is basically the flow of electrons, which are a fundamental form of matter. Lightning is in fact, very similar to the spark that you might see if you shuffle your feet and walk across the carpet and then touch a door knob? (Do not do it on purpose though!) Electrons are amongst the tiniest particles making up matter along with something called protons. Each atom (the fundamental building block of matter) has equal number of electrons and protons that balance each other.

When we shuffle our feet on the carpet, we pick up several electrons from the carpet. The small spark between your hand and the door was the transfer of electrons from your body to the door. This is because it is very hard to hold on to extra electrons, as they like to flow away immediately to maintain balance in matter.

Uneven heating of air causes a thunderstorm. A body of warm air is forced to rise by an approaching cold front therefore thunderstorm's form. In the case of lightning, the clouds up in the atmosphere contain several tiny ice crystals that rub together to produce charges. When these clouds come closer to earth, the electrons from earth jump up to the clouds and this causes a huge spark - that is, lightning. The flow of lightning in air is so fast that it pushes back some air and creates a channel in air. When the lightning has gone through, the air collapses back causing a loud rumbling sound - thunder. So thunder moves at the speed of sound, which is much slower that the speed of lightning which is almost as fast as light. You can read about a lot more experiments to do about lightning at Weather Wiz Kids .

Little Lion Experiment:

A very simple experiment to do involves the creation of charges and static electricity. Be careful and do this with adult supervision.

Items Needed:

A wooden or plastic ruler
Very small bits of paper, about half the size of your nail or much smaller than a penny
A plastic plate
A metal plate

Steps:

Spread out the bits of paper on the plastic plate and on a metal plate, keeping both plates on the floor.
Rub the ruler against the your head (that is, hair) or on a carpet a few times.
Now take the ruler close to the paper bits on the plastic plate. What happens?
Rub the ruler again on the carpet and take it near bits on the metal plate. What happens now?

Why Does Newspaper Turn Yellow?

2007-05-15T14:18:00.000-07:00

There are various paper products that we use in our everyday lives including paper plates, construction paper, tissues, brown paper grocery bags, printing paper, and newspaper. Have you ever wondered where all this paper comes from? These paper products are all made from wood, which is primarily made up of two polymer substances called cellulose and lignin. Polymers are formed from simpler molecules that are joined into large molecules that behave differently than the smaller molecules alone. Cellulose is made up of simple molecules that are linked together like chains, while lignin is made up of more complex molecules that are linked like circles or rings. The cellulose chains are easy to break apart, but the lignin rings are difficult to break apart because lignin acts like glue to make wood stiff so that trees can grow and stand upright.

Cellulose and lignin are usually separated from each other when wood is being processed to make paper. Cellulose is white in color, while lignin is dark in color. Most paper products are required to be white or very light in color like printing paper and paper plates, and these products are primarily made from cellulose. However, sometimes the visual quality of the final paper product does not need to be very light in color, so these paper products are made from both cellulose and lignin. These products include newspaper and brown paper grocery bags.

Lignin can turn yellow in color when it is exposed to oxygen or air especially in the presence of sunlight. The molecules in lignin will change and the circular links will become less stable. Since there is more lignin present in newspaper than most paper products, the newspaper will also eventually turn a yellow or brown color over time as it is exposed to air and sunlight. On the other hand, cellulose does not turn dark in color in the presence of air and sunlight.

For more information about how paper is made, see the website of the Energy Information Association.

Little Lion Experiment:

Items Needed:

1 sheet of newspaper that is only a day or two old
1 piece of printing paper (this paper can be used)
2 freezer bags
Access to sunlight
Access to an area where no sunlight shines, which could be a cupboard, closet, or drawer

Steps

Cut the newspaper into two pieces.
Place one piece onto a window sill or tape it to a window where sunlight shines.
Place the other piece into the freezer bag and shut it so no air can get inside.
Put the freezer bag with the newspaper in it into the area where no sunlight shines.
Repeat steps 1-4 for the printing paper.
Leave the pieces of newspaper and printing paper alone for 1 day and then visually compare all the pieces of paper. Continue the experiment and examine the different pieces of paper after 2, 3, 4, and 5 days to see if the paper changes much over time.

Questions:

How do the different pieces of paper visually compare with each other?
Are the ones exposed to air and sunlight darker in color than those pieces of paper that were not? How do the pieces of newspaper visually compare with each other?
How do the pieces of printing paper compare with each other?
Are there any visual changes between the same types of paper?

How Does the Sun Affect Our Lives?

2006-11-15T14:17:00.000-08:00

A few weeks ago, while watching the movie Superman, I found out that Superman derives his great power from the Sun. All of us on this planet derive most of our power from the sun too. The basic forms of light and heat energy are delivered directly to us from the Sun everyday.

Green plants need sunlight to produce food, which in turn can be eaten by us or by animals. Thus, the entire food chain depends on solar energy for survival. This is why in several ancient cultures the sun was respected and worshipped by the people.

Today's industrial world is supported by the energy sources of oil (petroleum), coal, and natural gas. However, did you know that all of these are essentially derived from solar energy too? These fuels, also known as fossil fuels, are formed from the remains of plants and animals which existed millions of years ago.

Again, it is the heat from the Sun that causes different parts on earth to heat up at different rates. This temperature difference between the air at various locations leads to winds, and consequently our use of wind energy. The evaporation of water to clouds followed by rains and the flow of water in rivers depends on the Sun too.

Thus, we depend on the Sun directly or indirectly for almost all our energy needs. The only form of energy that is not derived from the Sun is nuclear energy. Since solar energy that comes as heat and light is a free resource, we should try to use it as much as possible.

Remember to draw your curtains apart on sunny winter days to let the Sun in and bask in the warmth. In the summer and fall, we can also use the Sun to dry our washed clothes without using a clothes dryer! We can also use solar collectors and solar cells to tap the energy of the sun directly (ask your parents for more about this).

For more information and projects on solar energy, feel free to explore the links given below:

Government Energy Kids Site: http://www1.eere.energy.gov/kids/solar_heating_and_you.html
Solar Now: http://www.solarnow.org/
Solar Energy International: http://www.solarenergy.org/resources/youngkids.html

Little Lion Experiment:

We will try to do some experiments to show how different colored objects absorb or reflect light.

Items Needed:

A really sunny day! (it might be a little hard to get this!)
Plastic bottles - small soda bottles work well (2 or 3 bottles of same size).
Black paint or aluminum foil
Some tape
2-3 small balloons that would fit the bottle top.

Paint one of the bottles white if you can or use a clear bottle.
Paint another bottle with black or take some aluminum foil and wrap around the bottle with shiny side facing outward and tape it so the foil stays on the bottle.
Place the open end of one small balloon on the mouth of the white bottle and do the same for the black bottle. Make sure the balloon forms an air tight seal. Now place both bottles in bright sunlight.
Observe what happens. Record your observations.

Questions:

Which balloon started filling up first? Which bottle feels warmer?
Does heat make air expand?
Does a black object get warmer in the sunlight than a white object?
What would be a good color to paint a dog kennel if you wanted it to stay cool in the summer?

How Do Leaves Get Water from Roots?

2006-10-15T14:15:00.000-07:00

Plants need water, carbon dioxide and nutrients to live. Water and nutrients come to the plant from the ground, whereas the carbon dioxide comes from the air. The roots of the plant, which are under the ground, absorb water and nutrients for the whole plant above the ground. Have you ever wondered how water reaches the leaves of tall plants, especially the ones at the top? Water has to climb several hundred feet before it can reach the leaves of the top-most branches in some trees like oaks, pines or eucalyptus.

Capillary action and leaf pressure are two important factors that help move water in plants. Capillary action can simply be termed as the automatic movement of water through extremely narrow tubes known as capillaries (hair-thin in some cases) present inside the plant stem. In plants these tubes are called xylem. Capillary action helps plants in getting water to such heights against the downward force of gravity.

Leaf pressure is a property whereby the leaf is able to convey a message to the roots that the pressure of water is low in the leaf and hence it needs more water.

So what is it that helps the water drops stay together and climb up through the minute vessels in the plant body by capillary action? A physical property called surface tension helps water molecules stay together. Surface tension can be termed as the amount of force holding two molecules of the same kind together.

This property is quite high for water than many other liquids. Any impurities like dirt or salt in water tend to lower its surface tension. Because the surface tension for pure water is fairly high, when the water drops are absorbed by the tips of the plant vessels subsequent water drops cling on to the initial ones rising in the plant vessels and begin a journey to the top.

The high surface tension of water is also a reason why rain drops tend to be spherical. For more information on capillary action, read the article at http://en.wikipedia.org/wiki/Capillary_action.

Little Lion Experiment 1:

Items Needed:

A small glass of bottled water
A few leaves with waxy surfaces
A candle
Some flat cardboard pieces

You can apply wax to a cardboard piece by rubbing a candle lengthwise on the cardboard for a few minutes. This experiment is to show that surface tension is lowered due to addition of impurities.

Place a drop of water on the leaf or the waxes cardboard using an ink dropper.
Observe what happens to the water drop.
If the drop is still on the wax surface, try adding a few salt particles to the water drop.
Observe what happens.
If the drop of pure water had rolled off then mix one teaspoon salt to the water.
Add a drop of the salted water to the leaf/waxed cardboard.

Little Lion Experiment 2:

Items Needed:

A tall juice glass
A small thin cardboard piece
A small needle or thumb tack to make holes
Cotton thread (white thread works best)
Scissors
A small bowl of sugar (crystal sugar preferred)

This experiment will aim to demonstrate the movement of nutrients through capillaries.

Cut the cardboard piece to a size slightly larger than the juice glass opening.
Make several small holes in the cardboard piece using the needle or thumb tack (be careful).
Cut the thread into several pieces as tall as the glass.
Now push one thread piece through each hole such that the thread reaches at least below the half way mark in the glass. Keep the cardboard piece with the threads aside.
Now fill the glass halfway with water, add a spoon of sugar to it and mix till all the sugar dissolves.
Place the cardboard lid on top so that the threads all touch the water at least a little.
Leave the glass undisturbed for 2-3 hours.
Now carefully lift the lid off along with the threads and pour away all the water in the glass.
Let the thread dry over a few hours.
Observe what has happened on the thread. What do you see?

You should see some sugar crystals or at least some powdery white substance on the dry threads.

For more information on growing sugar crystals you can see http://www.crystalgrowing.com/recipes/sugar/sugar.htm or http://www.teachnet.com/lesson/science/crystals040999.html

Why Do Leaves Change Color in the Fall?

2006-09-15T14:14:00.000-07:00

Every fall we are treated to the grand spectacle here in the northeastern US. It is the fall foliage show in which leaves change color from a bright summer green to varying shades of yellow, orange, red, purple, and brown before falling off. The shedding of leaves occurs only in certain types of trees known as deciduous trees.

Many of us wonder why and how this happens. The story lies in the chemistry occurring in the leaves. Leaves are the food factories in trees. Leaves produce sugars in spring and summer when sunlight falls on the leaves as water and carbon dioxide are combined in the presence of a chemical called chlorophyll.

Chlorophyll is a green-colored chemical (also known as a pigment) that reflects the green portion of sunlight while absorbing other colors. This is what gives leaves their normally green color in spring and summer. Leaves contain several other pigments which are yellow, orange, red and brown in color, but the chlorophyll overshadows the rest.

During spring and summer, when days are long and bright, leaves are able to produce a lot of sugars; they send these sugars to the roots and the stem. But as fall sets in, days start getting shorter and the temperature begins to drop. This sends a signal to the tree that it has to prepare to shed its leaves and manage the winter on stored food (known as dormancy).

The tree cuts off the supply of nutrients and water to the leaves by the growth of a layer at the leaf-stalk connection. This event is called abscission. Once abscission sets in, the chlorophyll in the leaf breaks down quickly and loses its color. It is during this period (fall) that we see leaves of trees like birch, beech, cottonwood, hickory, willow, etc., turning yellow. Others, such as maples, sweetgum, and sumac, turn red. Purple is seen in dogwoods, some species of ash and some maples. Several oaks turn brown.

Some factors that control the colors include the temperature, the humidity (wetness), and the amount of sunlight during fall. Bright, sunny, cool days and chilly nights (without frost) create the brightest colors. The leaves exposed to bright sunlight might turn red, while those on a shady side may turn yellow. Wet weather usually leads to decrease in the brightness of the colors.

There are several places in US that have excellent fall foliage displays: New England, New York, Pennsylvania, even some parts of Idaho and Texas. But note that mountainous trees such as conifers (cedars, firs, pines, spruces, etc.,) do not change color and remain green throughout the year. Individual leaves on conifers sometimes stay on for three to four years.

Little Lion Experiment 1:

We will try to do some experiments to separate out the different colored chemicals in leaves (both green and fall leaves). Note that you must have adult supervision during these experiments because use of some items requires extra care and prior knowledge of safety. The process of separation of colors using chemicals is known as chromatography.

Items Needed:

Rubbing alcohol (ask your parent)
Hot tap water (ask your parent). Be careful not to hurt yourself.
A coffee mug
A large bowl or deep container that can hold the coffee mug
A pencil
Scissors (be careful while using)
Clear plastic wrap
Coffee filter paper
Green leaves and some yellow or red leaves

You will begin by cutting 2-3 green leaves in small pieces with the scissors.
Then you can crush them in the coffee mug and you can use a spoon to further mash them gently. Add some rubbing alcohol to the coffee mug--just enough to cover the leaves in the bottom.
Place the mug inside the large soup bowl or container and pour some hot tap water outside the mug so that it can get warm. [NOTE: this is the ONLY safe way to heat; do not try any other method. And keep the set-up away from all kinds of stoves]
Let the leaves soak in the warm rubbing alcohol for an hour or more.
Put plastic wrap over the mouth of the mug to slow evaporation of the alcohol.
If the water in the bowl gets cold, take the mug out, and empty the bowl and fill with new hot water. Replace mug back in position.
Wait until the liquid in the cup gets dark, showing that pigments are dissolved in it.
Using scissors, cut the filter paper (if you don't have filter paper, use paper towels) into one or two strips about 4 inches long by 1 inch wide.
Put the pencil down across the mouth of the cup and drape the filter paper across the pencil so that one bottom end touches the bottom of the cup through the liquid.
Let this stand for about 30-40 mins. What happens?

This works best if you seal the coffee cup with plastic wrap so that the alcohol does not evaporate. Sometimes you might have to soak for over 2 hrs depending on the leaves.

The pigments will move at different rates through the paper, and if you wait for 30 or 45 minutes, you will see them separate. The paper strips can be dried and you can keep them as a record. Next you can try this with yellow/red leaves. It is also a good idea to write down the name of the leaf (tree) with each strip if that is possible/known.

Little Lion Experiment 2:

This is a very simple way to preserve bright colored leaves:

Gather pretty leaves from trees.
Wash them gently to remove dust, and dry them with paper towels.
Place each leaf between two wax paper sheets. Keeping a cloth on top, ask an adult to run a warm iron over to press the wax paper to the leaf.
You can then cut the paper along the edges of the leaf and preserve it.

References:

What is the Chemistry of Cooking?

2006-08-15T14:12:00.000-07:00

Cakes, cookies and pies--who does not love these yummy baked goods? Have you ever seen these goodies being made or actually participated in making/baking any of these? There is lot of chemistry involved in our cooking.

If you had watched anyone bake a cake, you might have noticed them add a pinch of baking soda or baking powder with the flour. These chemicals help in leavening the flour (leaven: to make light/loose). The principle behind the use of baking soda depends on acid-base reactions that eventually release carbon dioxide gas to help the flour rise.

Acid-base reactions are chemical reactions between an acid and a base. Chemists define acids as substances that can accept electrons and bases as substances that can donate electrons. Acids are commonly found in our day to day life and they can be dilute or concentrated. Citric acid is an acid found in common substances such as lemon juice and orange juice. Acetic acid is found in vinegar. These are dilute acids, whereas concentrated acids are not generally kept around home as they can be quite dangerous.

Bases, on the other hand, behave chemically opposite to acids. Many household cleaners are basic or alkaline. When bases and acids react usually the exchange of electrons also releases heat. Most acids and bases react to form salts (minerals) and water. For example, the reaction between hydrochloric acid and baking sodium hydroxide (a base) would form water and common salt.

The main chemical in baking soda, sodium bicarbonate, contains carbon dioxide in bound chemical form. When it reacts with an acid, it releases carbon dioxide gas and water. This is why most cake recipes call for a small amount of vinegar or orange juice. The acid in these liquids reacts with the baking soda to quickly produce carbon dioxide gas that can bubble through the flour mixture, making it rise in the process.

There are also several other acid-base reactions that can occur even inside the body. The stomach contains acid that helps break down bonds in the food. It also reacts with alkaline matter in the food. If someone has acidity problems, the antidote is to eat/drink something alkaline to neutralize the acidity.

For more information on acid-base reactions in our body, see http://www.scienceclarified.com/everyday/Real-Life-Chemistry-Vol-2/Acid-Base-Reactions.html

Little Lion Experiment 1:

Items needed:

Vase or wide-mouthed clear jar
1/4 cup vinegar or lemon juice
3 teaspoon baking soda
Food coloring

Procedure:

Fill the vase/jar with clean water.
Add 3-4 drops of food coloring.
Add vinegar then add baking soda slowly into the beaker.
Drop in rice, buttons, pasta - and watch them rise and fall.

Experiment source: http://www.armhammer.com/myfamily/kids/magic_beans.asp

Little Lion Experiment 2: Writing With Invisible Ink

These are instructions for making non-toxic invisible ink using baking soda (sodium bicarbonate).

Items required:

Baking soda (not baking powder)
Paper
Q-tips
2 paintbrushes (at least 1)
Small cup
Cranberry juice or purple grape juice.

Procedure:

Mix equal parts water and baking soda to make a paste. We recommend starting with a small amount (about 2-3 table spoons) first. Sometimes you can dilute it more.
Use the q-tip or paintbrush to write a message onto white paper, using the baking soda solution as 'ink'.
Allow the ink to dry.
To read the message paint over the paper using another brush with purple grape juice. The message will appear in a different color.

Source: http://chemistry.about.com/cs/howtos/ht/invisibleink2.htm

How Do Fireworks Work?

2006-07-15T14:10:00.000-07:00

You probably saw, or at least heard, fireworks earlier this month for July 4th celebrations. The idea that explosions cause loud sounds along with bright lights is commonplace. You've seen it with lightning, sparklers, and a host of other things. But how do firecrackers work? What gives them their beautiful colors and carefully-arranged patterns in the sky?

Fireworks have been around for centuries. They were invented in China, but are now enjoyed all over the world. A firework is basically a timed explosion of a precise chemical mixture in order to produce loud noises and colored lights after the firework has shot up into the sky.

Each firework is composed of two cylinders: a small lifting charge cylinder on the bottom and a large shell on top. The lifting charge is the first source of fuel for the firecracker. When lit, it explodes in order to propel the shell upwards like a rocket.

The shell consists of four main parts. The container (made of paper and strings) wraps around the rest of the shell to keep everything in place. The actual color-producing chemicals (also known as color-emitters) are bundled up into small stars which can be arranged so that the individual bursts of light will form a neat flower-like pattern in the sky. The bursting charge is the fuel for the shell and it is located at the core of the cylinder so that the stars will explode outwards.

The last part of the shell is a fuse which carries the spark from the lifting charge cylinder to the stars in the shell. Since it takes time for the spark to travel, the fuse allows engineers to control the length of time between when the firecracker takes off and when it will explode. Increasing the length of the fuse will delay the explosion for a longer amount of time so that the fireworks will burst even higher in the sky.

Until the production of chlorates (pronounced KLOR-ates) in the 1800s, fireworks only came in yellow and orange varieties since those are the only colors (besides grey) that resulted from burning the firework shells. The addition of chlorates allowed chemists to produce red and green explosions. Safe chemical mixtures that produce blue and purple flames were not developed until the 1900s.

Obtaining pure bright colors is extremely difficult when dealing with fireworks. Many of the color-emitters are so fragile that they would decompose (break down into other chemicals) if stored in the shell of a firework. To solve this problem, chemists devised mixtures of other chemicals that will react to form the desired colored compounds once the firecracker is ignited.

Another dilemma is that, during the explosion, many of the byproducts (unwanted chemicals formed in the reaction) are gray or yellow so these compounds can make the color of the flames look washed-out.

For more information on fireworks, and an interactive demonstration, visit http://science.howstuffworks.com/fireworks4.htm on the web.

Little Lion Experiment:

To see how chemical reactions can produce colors that you might not expect, try this experiment (it's best to have an adult around for the first part). The chemical reactions used in fireworks are very dangerous, so we will be using other chemicals to illustrate the point [do not try to make your own fireworks!].

Grate about half a head of red (purple) cabbage (be careful not to cut your fingers). Place the grated cabbage in a pot with enough water to cover the cabbage, and boil it for 20-30 minutes. The water should be dark blue or purple at this point (if it's not, then boil it for a few minutes more). Then, pour the liquid (careful - it's hot!) through a strainer into a bowl. Throw out the cabbage pieces in the strainer. Let the purple liquid cool.

Pour a few tablespoons of white vinegar or lemon juice into a small cup. In a different cup, mix some detergent or baking soda in water. Then add a few drops of your cabbage juice to each cup. See what happens. Are the solutions the colors you expected?

Why Can't Oil and Water Mix?

2006-06-15T14:09:00.000-07:00

Have you ever wondered why oil and water do not mix? Chemistry gives us a clue, saying that liquids which are made of similar molecules tend to mix with each other easily. Molecules are some of the fundamental building blocks of matter.

Oil and water are made of different kinds of molecules which interact differently with each other so they do not tend to mix. The molecules of water, for instance has a more "electronic interaction" whereas oil has "non-electronic interactions."

Further, a drop of oil is usually lighter than an equally sized drop of water, so usually oil floats on top of water when the two are present in the same place. In other words, water is more dense than oil. You might have seen this when you place a drop of butter on top of a hot soup. Soup is mostly water and butter has a lot of oil in it, so as the butter melts it floats as a thin layer on the soup.

This is the same thing that happens when an oil spill occurs if a ship carrying petroleum (crude oil) breaks while on the sea. The oil spills and floats on top of the sea water causing lot of pollution and problems to aquatic life. Of course, oil spills occur very rarely and the more common reason for oil in the ocean water is from cleaning and rinsing of ships.

Just like cleaning oil spills can be a problem for environmental scientists, removing grease from clothes is a problem for all of us. Fortunately, although oil and water do not mix, there are chemicals like detergents which are attracted to both oil and water and can aid in their mixing.

When a detergent is added and mixed up between the oil and the water, it holds hands with oil and water molecules and helps in getting the oil rinsed off with excess water. Such a mixture where oil and water can finally be together with the help of another substance is called emulsion.

Some emulsions which are actually edible happen to be milk, butter, mayonnaise, etc. Of course these are not made with detergents! In summary, oil and water will not mix by themselves because of many different properties, but they can be made to mix with the help of things like detergents or emulsifiers. Since oil floats on water, a lot of fun (but messy) experiments can be done using oil and water.

For fun experiments about oil and water, see http://www.epa.gov/nps/kids/SHAKE.HTM.

Little Lion Experiment:

We will learn how oil and water interact . Caution: These experiments can all get pretty messy, so do NOT attempt them on carpeted floors at all. Also, it is advised to not do it on a wooden floor either, as any spill can be slippery and dangerous. These are best done on a garage floors, preferably with a lot of paper towels around and a small box of sand nearby.

You will need:

Water
Vegetable oil
Glass jar or clear drinking glass (an old pasta sauce bottle will do the job)
Food coloring (optional)
Salt
Detergent powder or dishwashing liquid.
A wide glass bowl.

Steps: Experiment 1:

Pour water halfway into the glass jar.
Pour quarter cup oil on top of the water.
Let the liquids settle and observe what happened, which layer is on top, etc.
If you have food coloring add a drop or two to the top surface and wait and see what happens.
Another thing you can do is, sprinkle some salt to the top of the oil and see what happens.
You can also now try pouring a small amount of water using a table spoon to the top of the oil layer and see what happens to this new water.
Add some detergent powder or a few drops of dishwash liquid and mix things up with a spoon. Allow mixture to settle and see what it looks like now. Do you still see two clear layers?

Steps: Experiment 2:

Pour water halfway into the glass bowl.
Take a table spoon of oil and try to form a small region of oil film on the water.
Try to see if you can break the oil film into several small regions with your spoon.
Then try putting them back together into one film.
Sprinkle some detergent on top of the oil and mix it up.
Now see what has happened to the shiny oil film.

What is Wind Energy?

2006-05-15T14:07:00.000-07:00

Wind energy! This is one energy form which humans have been using for several centuries. It is a type of mechanical energy, which means it is energy derived from motion. Do you know how the wind is caused? Ultimately, it is due to the Sun. The energy of the Sun heats up different parts of the air in the earth's atmosphere unevenly.

The farther you are from the equator, the lesser is the amount of the Sun's energy reaching the surface. This difference of heating causes the air in some places to get heated more, whereas the air in some other parts is still "colder." Since warm air is lighter than cold air, the warmer air rises up leaving a void which is taken up by cold air moving in from nearby places.

This movement of air is the wind. Since the earth is also rotating at the same time, the air also moves across the surface of the earth causing wind. The same principle can happen locally too, especially near the sea.

Sand gets heated much more faster than water, and so during the day the air above the sand (on land) gets hotter faster and tends to rise up. The air above the water is still cooler and moves in towards the land, causing a breeze during daytime.

At night, the reverse occurs as the sand cools off faster but the water still has some warmth gained during the day. So the air above the water is warm and now rises up, and the air from the land flows towards the sea.

The power of the wind has been used for moving boats, grinding grains or drawing water for several hundred years. It is now used to generate electricity too. The windmills are like reverse fans. Wind mills typically have 2-3 blades (called turbine blades) and one generator.

The moving blades rotate a magnet which is housed inside set of copper wires. When a magnet rotates inside the copper wire, it causes electricity to flow in the copper due to magnetism. Thus electricity is generated. In Pennsylvania, Somerset county & Williamsport are good places for wind power. When a lot of windmills are together at one place they are called wind farms!

For information on wind energy see the website by the US Department of Energy: http://www.eia.doe.gov/kids/energyfacts/sources/renewable/wind.html and the website by Alliant at http://www.powerhousekids.com Look under Fun & Games (purple menu bar on webpage) for "Cool Projects to Try at Home."

Little Lion Experiment:

We will learn how to make a small wind runner or wind fan. You will need some paper (from any notebook or copier) or long slender leaves (optional), a thumbtack, a pencil with eraser at one end, and scissors.

You can make wind runners using long slender leaves or paper. For making a wind runner using a leaf, please see the diagram which illustrates how to cut off one half of the leaf on either side of the center line leaving some space in the middle to make a hole. It is best to pick slender leaves that are green, a bit sturdy and have a smooth edge all along.

You can then pierce a small hole with a thumbtack through the hole and push it into the eraser of a pencil on the other end. Once the leaf is secure between the tack and the pencil, run around and see the leaf rotate like a fan. You can also try fixing this to your bicycle handle bar and watch it spin fast!

How Do Plants And Water Break Rocks?

2006-04-15T14:06:00.000-07:00

You have probably seen people use big hammers to break rocks (in movies) or bulldozers to knock down large buildings. Did you know that plants too can break rocks? Have you seen tiny plants come out of cracks in the road or a concrete sidewalk? It is amazing to see a tiny plant break apart a big rock as it grows in a crack in the rock.

Plants exert a large amount of force on everything around them. All this hidden strength in plants and seeds come from the process of imbibition. Imbibition simply means taking up or absorbing water. This process can be understood by knowing what plants are made of.

Plants are made up of millions of little cells. Cells are the building blocks of living organisms. In plants, the cells are close together but are still set apart by a large number of pores, empty spaces between cells in plants.

Each cell in a plant has a flexible outer covering called cell wall. When the plants or seeds are near water, they absorb the water into their pores and also into the cells. Since the cell wall is flexible, it allows the cell to expand in size and yet not break.

The expansion of all cells is what causes a seed to enlarge so much or wood to swell. Did you know that long, long ago (several thousand years ago) the people who built pyramids in Egypt and temples in India used the power of the swelling in wood to break large rocks?

They used to place wooden wedges in cracks of large rocks, pour some water, and wait. In a few days the wood would swell up and slowly crack the rock open. Then the broken rocks were used to build pyramids and stones. The ancients even used the swelling to wood to lift the rocks, but that story is difficult to explain here!

Other fun experiments on plants are at: http://mgonline.com/experimentsforkids.html. It is going to be spring time so growing plants is the fun thing to do! For information on pyramids and temples visit: http://www.historyforkids.org/learn/egypt/architecture/egyptarchit.htm and http://www.templenet.com/tamilnadu.html.

Little Lion Experiment:

The great strength of wood-based materials when they expand due to water absorption can be easily shown at home. Seeds and beans (whole dry beans) are similar to woody matter and swell if soaked in water over a few hours. The interesting thing with soaking beans or seeds in water is that you will end up getting sprouted beans after a couple of days.

This experiment can be set up in few minutes, but will show results only after few hours, so some patience will be needed. You will need these materials:

dry beans (green mung beans, or red kidney beans or garbanzo beans - you have to use dry beans)
a small plastic container with a lid (yogurt containers with clear lids work best)
water
a large plastic bowl or plate

Steps:

Fill the container with dry beans leaving small amount of room at the top.
Set this container into the large bowl or plate.
Add water slowly to the beans until you see water reach the top.
Place the lid on the small container and close it firmly. If you use plastic wrap, you can clasp it tightly to cover the top and then put a rubber band around the container wall.
Write down the time, and check the container at intervals of 1 hour.

Why Is Natural Gas A Cleaner Energy Source?

2006-03-15T14:05:00.000-08:00

Coal, oil, and natural gas are all important fossil fuels for heating our homes, generating electricity, and fueling vehicles. These energy sources are called fossil fuels because they are formed from the fossilized remains of plants and animals that lived thousands of years ago.

However, even though all three fossil fuels are formed from decaying organisms (living things), both coal and oil produce a variety of harmful byproducts when burned, while natural gas only produces carbon dioxide and water vapor when burned. This is due to differences in their final chemical compositions, which are due to the different processes (trapping, compaction, and heating) naturally taking place underground.

In general, natural gas has the simplest chemistry and is only made of one carbon atom and four hydrogen atoms (atoms are the fundamental building blocks of all matter), while coal and oil are much more complex.

The simple chemistry of natural gas allows it to have almost 100% energy conversion when it is being burned. This means that the majority of the fuel is being utilized for power needs and only a small amount of the fuel is not being used for power needs.

On the other hand, the harmful byproducts that coal and oil produce are a result of their incomplete energy conversion. Therefore, natural gas is considered to be the cleanest burning fossil fuel.

For more information and fun games on natural gas safety, check out Sierra Pacific's Natural Gas Safety World at http://www.sierrapacific.com/kids_safety/gas/index.html.

And if you ever visit Centre County, you will find that the CATA buses around town are actually running on natural gas! Check out their website for more information on these environmentally friendly buses: http://www.catabus.com/accngprog.htm.

Little Lion Experiment:

Natural gas collects underground by seeping into and passing through reservoir rock (a layer of spongy rock). To keep the natural gas from moving or leaking to the earth's surface, a different layer of rock called cap rock (a layer of solid rock) exists above the reservoir rock. The combination of these different rock layers allows the natural gas to accumulate until it is ready to be used for energy needs.

This experiment will help you to understand the different ways that natural gas can be trapped underground. You will need these materials:

sand
clay
two 8 oz. wide-mouth glass jars
16 oz. of water
magnifying glass

Steps:

Feel the sand and clay with your hands. Do they feel different?
Examine the sand and clay with the magnifying glass. Do they look different?
Put the sand into one glass jar and the clay into the other glass jar. Fill each jar about 2/3 full.
Add the water to each jar to fill the remaining space.
Observe the water's behavior - Is it passing through the sand or clay to the bottom of the jar? Or is it sitting on top of the sand or clay?

The material that allows the water to pass through is acting like reservoir rock underground, which allows water to seep in. This is similar to how natural gas accumulates underground. The material that does not allow the water to pass through is acting like cap rock because it is stopping the movement of the fluid. This explains how natural gas can be trapped underground.

Why Do We Laugh

2006-02-15T14:03:00.000-08:00

We've all had the experience of laughing at something funny, but what exactly are humor and laughter? From a biological standpoint, laughter is a certain set of vocal sounds and physical movements occurring together (the biological study of laughter is called gelotology).

Laughter has also been shown to be beneficial to our general health. So, laughing is not only fun, but it's also good for you! That's lucky for us, since the average person laughs 17 times per day. That amounts to about one episode of laughter per waking hour!

Humor is a very complex topic. Realizing that something is funny involves many of the same areas of the brain as problem solving does. Humor also involves the frontal lobe (the part of the brain that allows us to experience social emotions).

Brain activity then spreads to the occipital lobe, which processes signals. Finally, the motor (i.e. movement) portions of our brain produce signals to bring about the physical movements associated with laughter.

Researchers have found that humor falls under 3 main categories:

Surprise: something strikes us as funny when it is contrary to what we expected to happen. Whenever someone starts a sentence, or an action, our brains predict what will follow. So, when a comedian sets up a joke, we think we know where the story is headed, but the punch-line surprises us, and so our brain interprets that as being funny.
Feeling superior: as much as we don't like to admit it, sometimes we laugh at others. mistakes or misfortune. This is what is commonly known as "making fun of someone." This humor is the result of our enjoying the emotion of feeling superior to the person we are laughing at. This type of humor is not polite and is not particularly kind either, so we often train ourselves not to indulge in it.
Relief: humans laugh at stressful situations as a way to cope with stress and anger. For example, if you're walking to school without an umbrella, and it starts to rain, you may feel frustrated or angry, but you will most likely chuckle at the situation. "Nervous laughter" also falls under this category since it serves to reduce tension in social settings.

Little Lion Experiment:

Laughter is a very important part of our social interactions. Studies have shown that people are much more likely to laugh at something funny when they are with other people than when they are alone. This explains why watching a comedy in your living room just doesn't live up to the experience of watching the same movie in a crowded movie theater.

For a week, keep a tally of how many times per day you laugh. Record whether you were alone or whether you were with other people each time you laughed.

Estimate how many waking hours (i.e. hours when you weren't asleep) you spent alone. Divide the number of times you laughed alone by the number of hours you were alone. This will give your rate of solitary laughter (how many times per hour you laughed alone).

Then, divide the number of times you laughed with other people by the number of hours you spent with other people. This will give your rate of social laughter (how many times per hour you laughed with other people).

Compare your rate of solitary laughter with your rate of social laughter.

Why Are Arteries and Veins Different Colors?

2006-01-15T14:02:00.000-08:00

If you've ever stared at the blood vessels (veins and arteries) in your wrist, then you've probably noticed that your arteries look purple and your veins look blue. However, this is an illusion of nature; arteries and veins are actually both whitish in color! This illusion is due to the way that different wavelengths of light pass through our skin.

White light is composed of the different colors of visible light (red through violet). Each of the colors has its own set of wavelengths, with red having the longest wavelengths and violet having the shortest wavelengths.

Long wavelengths penetrate our skin more easily than shorter wavelengths do. So, red light can penetrate deeply enough into our skin that it reaches our blood vessels, where it is absorbed.

In contrast, blue and violet wavelengths are so short that they can not penetrate our skin very well. This means that they are reflected back at our eyes before they have a chance to be absorbed.

Therefore, when we look at blood vessels under our skin, we see the blue and violet light that is being reflected back at us, so our veins and arteries appear to be blue and purple even though our blood is not actually blue!

But why aren't veins and arteries the exact same color as each other? The answer revolves around the fact that arteries carry oxygenated blood (blood that contains a lot of oxygen) away from the heart, while veins return the deoxygenated blood (blood with less oxygen) from the tissues to the heart. [An easy way to remember this difference is to think arteries = away.]

When we inhale air, oxygen passes from our lungs into our deoxygenated blood. This addition of oxygen means that the blood is now oxygenated. The heart then pumps the oxygenated blood through the arteries to the rest of the body, where some of the oxygen is then used by our tissues (which make up our bodily organs). The leftover (deoxygenated) blood is then returned to the heart by our veins.

Oxygen changes the color of blood in such a way that oxygenated blood is a very bright red color, while deoxygenated blood is a darker red (not blue as some people believe). Now it should make sense why arteries are a bit redder than veins!

Little Lion Experiment:

Besides color, another difference between arteries in veins is that arteries pulsate (expand and contract) much more than veins do as blood flows through them. The slight changes in the shape and size of our veins is so slight that you can't even feel it.

In contrast, you can feel the pulsing of your arteries just by pressing your finger gently over an artery. This is called "finding your pulse." The two easiest places to find your pulse are on the groove of the underside of your wrist and on your neck right below you ear.

A person's pulse reflects how often blood is pumped between their heart and their blood vessels. In other words, it shows how hard their heart is working to get enough oxygen to their body.

To see how your pulse changes with the changing demands that you place on your body, place a watch or clock with a second hand in front of you. Sit still for 5 minutes, then press your index finger gently over your wrist or one side of your neck. Record how many times your feel a pulse in 12 seconds. Then multiply this number by 5 to get the number of pulses in one minute (5 x 12 seconds = 60 seconds = 1 minute). This number is called your resting pulse.

Next, if you are physically fit to do so, jog in place for a minute, do 30 jumping jacks, or do some other safe form of exercise for about 1 minute. Immediately after that, sit down and record how many times your feel a pulse in 12 seconds. Then multiply this number by 5 to get the number of pulses in one minute.

Compare your resting pulse to your pulse just after your exercised to see how much harder your heart has to work when you move around. This difference shows that physical activity requires extra oxygen since your tissues need oxygen in order to make energy.

How Do Microwaves Work?

2005-12-15T14:01:00.000-08:00

When you drop a stone into a pool of water, you see waves. Ripples in the water bounce up and down. The waves form circles around the spot where the stone hit the water. The ripples start small but then they move away from the center, in bigger and bigger circles. The frequency of the waves represents how quickly they are bouncing up and down.

Microwaves are a type of radio wave. Appliances such as your radio, cordless telephones, cell phones, and television all function by radio waves. Radio waves are like water waves, but you can't see them.

In addition, radio waves work on a much smaller scale. Everything in the universe is made up of atoms (the fundamental building blocks of all matter). The most mobile parts of an atom are called electrons. When radio waves hit an object, they make the electrons in that object bounce around.

High frequency radio waves have more energy than low frequency waves do.

Microwaves are very high-frequency radio waves. They are used in cell phones, wireless Internet, and in microwave ovens.

The waves in cell phones and wireless Internet do not get very much electricity, so these waves are very weak. In contrast, lots of electricity runs through a microwave oven, so microwaves are strong.

Just as water waves make things move, microwaves make atoms move. The atoms bump into each other, and the resulting friction makes the food get hot.

In a microwave oven, a radio makes microwaves and sends them in one direction. They are aimed at a spinning fan that sits above or beside the food inside. Sometimes you can see the fan, but most of the time it is hidden behind plastic.

When the microwaves hit the spinning fan, the waves bounce off and hit the food. The microwaves then get absorbed by the fats, sugars, and especially water in the food. Once absorbed, the microwaves cause the electrons in the food to vibrate. This generates heat, which can then evenly heat up your food.

Microwaves can bounce around inside the oven. The metal walls of the oven keep the microwaves from escaping into the surroundings. Even though you can see the food while it's cooking, the microwaves won't bounce out of the glass door because the metal screen stops them. Still, it is not good to be too close to the oven when it is cooking.

For more fun information about the science of microwave ovens, you should explore these interactive websites!

Dr. Electric's Microwave Oven Laboratory at http://www.discovery.panasonic.co.jp/en/lab/lab02mw/
Professor Lee's Microwave Oven Laboratory at http://www.colorado.edu/physics/2000/microwaves/
Little Lion Experiment

The microwaves used in microwave ovens are specially designed to heat up water molecules since food is mostly water.

Get two crackers that are the same size and type. Moisten one cracker with room-temperature water. Put both crackers onto a napkin and microwave them for 7 seconds. Safety note: wait 20 more seconds before opening the microwave door so that the heat will have a chance to spread out evenly over each cracker! Feel both crackers with your finger. Which one is warmer? Why?

Why Do Plants Wilt?

2005-11-15T14:00:00.000-08:00

If you've ever forgotten to water your house plants, then you've probably noticed that they begin to wilt. Most of us naturally know that wilting plants need water, but exactly why is it that dehydrated (thirsty) plants wilt?

The answer is that plant cells contain many organelles (compartments), one of which is a very large vacuole (storage compartment) for water. When filled with water, this vacuole pushes out against the cell wall (a rigid layer which wraps around the plant cell to support it). This resulting outward pressure is called turgor pressure.

When it rains, or when you water a house plant, some of the water absorbed by the plant's roots is used to carry out cellular processes, some is used to transport nutrients (the plant's equivalent of an animal's blood circulation), and the leftover water is stored in vacuoles in the cells.

So, when a plant is well-hydrated, its vacuoles swell with water. Thus, the turgor pressure inside each cell is high. This supports the wall of each cell and makes the plant cells stiff. This stiffness is what allows plant stems to stand up straight (plants rely on turgor pressure since they do not have bones to support their "limbs" against gravity).

In contrast, when a plant gets dehydrated, it must use its vacuoles as a source of water since water is so important for every cell to function. So, some of the stored water must exit the vacuoles so that it can be used. This is similar to a town's water tower: when the town is well-supplied with water, the tower stays full, but when there is a water shortage, the stored water in the tower is drained out and used to support the townspeople.

As you can imagine, when the vacuoles are drained, they shrink and thus do not push outward on the cell wall anymore. This lack of turgor pressure causes the plant to wilt.

Little Lion Experiment:

Cut a grape in half and peel the skin off of it. If you don't have grapes, then cut a thin (1/4") slice of an apple. Notice how the fruit is rather stiff.

Next, to cause dehydration, cover the piece of fruit with salt for 10 minutes. The salt will draw some of the water out of the fruit. For the best results, scrape the wet salt off of the fruit and replace it with a new sprinkling of salt every 2 minutes.

Now, you have dehydrated the fruit cells so that their water vacuoles are depleted (i.e. they contain less water than they used to). This is similar to what happens when you forget to water your house plants. Feel the fruit to see how dehydration affected the stiffness of the plant. Can you explain your results with regard to turgor pressure?

Food for thought: if you left the grape in salt for a very long time, you'd end up with something similar to a raisin. A raisin, after all, is just a dehydrated grape! It still has the same amount of skin around it, but that skin is wrinkled because the volume of the raisin is much less than the volume of the original grape. This difference in volume shows how much water was lost. So, since grapes are so much larger than raisins, you can see that the main component of grape cells (and in fact all living cells) is water!

Why Do Onions Make Us Cry?

2005-10-15T13:59:00.000-07:00

Many people enjoy the taste of onions in their meals. Indeed, the average American eats about 18.3 pounds of onions each year. Onions are healthy components of the human diet because they contain vitamins B and C, protein, calcium, iron, and quercetin (an antioxidant, which helps to neutralize harmful substances in our bodies that cause tissue damage and aging). In addition to being full of nutrients, onions are low in fat and sodium.

However, if you have ever cut into an onion, it is likely that your eyes filled with tears. Why does this happen? How can we enjoy the taste and benefits of onions without the tears? Read on to find out.

When you cut into an onion, an enzyme (i.e. a molecule that speeds up chemical reactions) called lachrymatory-factor synthase is released into the air from the ruptured onion cells. This enzyme converts some of the proteins in the onion into sulfenic acids, eye irritants which are responsible for the flushing action of our tears. Sulfenic acids are also responsible for the strong odor of raw onions.

So, how can we enjoy the benefits and the great taste of onions without the tears? Here are several methods that can reduce the amount of sulfenic acids that reaches the eyes:

After peeling, put the onion in the refrigerator or freezer for a few minutes to slow the speed of the chemical reaction.
Run the onion under cold water while slicing, or cut it underwater.
Cook the onion before slicing.
Do not rub your eyes, because they will be coated in irritating compounds from the juice of the onion.
Cut the onion in a plastic bag with the bottom cut out.
Turn the vent fan on high and place your cutting board next to the stove top.
Try pouring a small amount of white distilled vinegar on your cutting board before slicing.

Over time, it is even possible to develop a tolerance for the chemical, reducing the amount of reaction.

Go on, put your new eye defense skills to the test with the help of a parent or other handy adult with the Little Lion experiment of the month!

Little Lion Experiment:

This onion soup recipe from the National Onion Association is full of flavor, and makes a tasty treat. To make it, you will need:

4 large yellow onions
6 tablespoons butter or margarine
1 tablespoon sugar
2 quarts reduced sodium chicken broth
Salt and pepper to taste
baguette French bread, sliced and toasted
Grated Romano cheese
An adult to help you

To begin, slice the onions, using any of the above methods to reduce eye irritation. Be careful with the knife, and always point the sharp part of the blade away from you when cutting. Melt the butter or margarine in a large saucepan that holds at least 4 quarts. Next, add the onions and cook over medium heat, stirring often, for 12 minutes or until tender and golden. Add sugar and stir for one minute. Next add broth, cover, and bring to a boil. Reduce heat, and simmer for 12 minutes. Season the soup with salt and pepper to taste.

Finally, ladle soup into bowls and top with toast and cheese. Enjoy!

What Are MagLev Trains?

2005-09-15T13:58:00.000-07:00

Engineers and scientists not only invent new modes of transportation, but they also look for ways to make existing vehicles faster, safer, quieter, and more energy-efficient (i.e. make them use less energy).

One area of current research is the MagLev train. MagLev stands for Magnetic Levitation. Demonstration MagLev trains have already been built in Germany and Japan, where they have reached maximum speeds of 250 to 350 mph!

This is still not as fast as commuter airplanes fly (~550 mph), but it is still a huge improvement over conventional trains, which travel at about 80 mph. So, you can see that a trip on a MagLev train would be about 3 to 4 times as fast as the same trip on a regular train! This is because MagLev trains don't touch the tracks, so only air resistance slows them down (vs. the large amount of friction between the tracks and wheels of a regular train). This also makes MagLev trains much quieter than regular trains.

Now, let's look at how MagLev trains work. Every magnet has two opposite sides: north and south. If you've ever played with magnets, then you know that opposites attract and likes repel. In other words, north and south attract, while two norths or two souths will push away from each other.

Imagine that you have one large flat magnet laying on a table so that its north side is facing the ceiling and its south side is flat against the table top. If you put a smaller magnet on top of the larger magnet so that their north sides touch, what will happen? The two magnets will repel each other. If this force is strong enough and if the small magnet is light enough, then the small magnet will levitate (float) above the larger one.

MagLev trains use the principle that we just discussed, but on a much larger scale. Most MagLev train designs rely on repulsion between magnets on the tracks and magnets on the bottom of the train.

In our tabletop example above, we got the small magnet to levitate but not to move forward. Thus, a power supply is needed to change the magnetic forces behind and in front of the train in such a way that the train is pushed and pulled forward.

How are the power supply and the magnets related? Unlike permanent magnets (e.g. kitchen magnets), the magnets used for MagLev trains are electromagnets (their magnetic forces are created by electricity). Since these electromagnetic forces rely on a power supply, their strength and direction can be changed by altering the power supply.

Current research is focused on making this power supply more energy-efficient, and thus cheaper to maintain. Once the price of operating the train is reduced, MagLev train tickets could be sold at reasonable prices to the general public.

Little Lion Experiment:

As objects move further apart, the magnetic attraction or repulsion between them gets weaker. To observe this relationship, obtain a few different strong refrigerator magnets. Tie a piece of string (about 8" long) onto a small metal paper clip. Then, tape the free end of the string onto the table.

Hold one refrigerator magnet next to the paper clip then raise the magnet until the string is pointing straight up. Slowly pull the magnet upwards one millimeter off of the paperclip. If the paperclip drops, then the magnet is fairly weak. If the paperclip stays suspended, then the magnetic attraction is still strong enough to fight the forces (mostly gravity, but also the tension in the string) pulling the clip downwards.

Continue moving the magnet upwards. Eventually, the paperclip will drop. This is when the magnetic force pulling it upwards becomes less than the forces of gravity and tension pulling it downwards.

These downward forces depend on the string and the paperclip, so they are the same no matter which magnet is used. So, if you use the same paperclip and string each time, then the distance at which the paperclip drops depends only on the strength of the magnet.

Why Do the Stars Change?

2005-08-15T13:57:00.000-07:00

When you gaze up at the night sky on a clear night, you have probably been able to identify the North Star as well as certain constellations (recognizable groupings of stars) such as the Big Dipper and Orion.

Other famous constellations include the twelve zodiac signs, which are based on ancient mythology. The two zodiac constellations that are assigned to the month of August are Leo and Virgo. Oddly enough, these two constellations are not among the easiest to see this month.

The constellations most easily visible in August are: Sagittarius (The Archer), Telescopium (The Telescope), Lyra (The Lyre), Scutum (The Shield), and Corona Australis (The Southern Crown). For diagrams of these constellations, as well as information on their important features, visit http://www.seasky.org/pictures/sky7b08.html .

Stars don't actually travel across the sky, so then why does the night sky change according to the season? In other words, why can you only see certain constellations during certain months?

The answer is that the planets in our solar system revolve (travel in a circular path) around the Sun and rotate (spin). The Earth rotates towards its eastward direction, and each rotation represents one day.

The part of the Earth that faces the Sun experiences daytime, while the side facing away from the Sun experiences nighttime. Thus, the stars that we see on a given night are only those that face the nighttime side of the Earth on that particular night.

So, since we are moving but the stars are not, our position changes in relation to the constellations. To better visualize how the movements of the Earth affect our night sky, do the Little Lion Experiment as directed at the end of this article.

While this concept may seem strange at first, think about how the position of the Sun in our sky changes during the course of a day. It is not the Sun moving, but the Earth moving that causes the Sun to appear as if it were moving across the sky. Our view of other stars is like this except the movements are less obvious since they are so much further away from us than the Sun is.

The Earth rotates more or less in a sideways (versus upwards or downwards) direction. It is as if the Earth were spinning about a line running from the North Pole to the South Pole. This imaginary line is called the axis of rotation.

However, the actual axis is tilted a bit. This is similar to a top spinning when it is just starting to tip over. The tilted axis of Earth is believed to be a result of the Earth having been hit by a large object (like an asteroid) a long time ago.

Little Lion Experiment:

To make a model of our solar system, put a ball on the table to represent the Sun. Use an orange or plum to represent the Earth (which revolves in a counter-clockwise direction). Pick an object in the room (like a clock on the wall) to represent a specific constellation, while a spot on the ceiling directly above you can represent the North Star.

Put a small piece of tape on the fruit to represent where you are. Stick a straw into the fruit where the tape is, pointing diagonally upward. Imagine standing where the tape is on your model Earth. What you could see through the straw represents the part of the sky you see when you look outside.

By acting out how the Earth rotates and revolves around the Sun, you can see when you experience day and night, as well as how your view of the universe (represented by the room in which you are sitting) changes.

To compare your model to the actual changes in the night sky, find the North Star, as well as one or two constellations that are easy for you to spot. Then, track their positions in the night sky over the next few weeks (once per week is sufficient).

Using your model, can you see why the position of the North Star stays relatively constant, while the constellations seem to move across the sky?

What Are Sloths?

2005-07-15T13:56:00.000-07:00

When many people see a sloth for the first time, they think that it is either tired or lazy. In fact, the word "slothful" means "lazy." Sloths are not actually weary or lazy, but many people make these false assumptions because sloths sleep so much (up to 15 hours per day!) and because they move at an incredibly slow pace.

Sloths are so sluggish because they are designed to live off of very little food (food is how animals get their energy). Since sloths do not eat many calories (energy stored in food), they have very little energy to carry out their bodily processes like digesting food and regulating body temperature. In other words, sloths have a very slow metabolism (the rate at which their bodies use energy).

There are two types of sloth: the two-toed sloth and the three-toed sloth. These names refer to the number of toes on the animals' forelimbs (arms). However, there are other differences as well. Two-toed sloths have longer legs, do not have tails, and are omnivores (they eat plants and small animals). In contrast, three-toed sloths have shorter legs, are equipped with tails, and are herbivores (they only eat plants). Both types grow to be 1 1/2 to 2 1/2 feet long.

Two-toed and three-toed sloths both evolved from the Giant Ground Sloth, an herbivore that was about the size of an elephant! For reasons that are still unknown, the Giant Ground Sloth became extinct in North America about 10,000 years ago. As a result, the sloths that we see today are native only to Central and South America.

In contrast to the Giant Ground Sloth, modern day sloths rarely go down to the ground. Instead, they spend virtually their entire lives hanging upside down in trees!

This upside down position is the reason that many of their internal organs (e.g. stomach and liver) are located in different places than they are in other mammals. In addition, a sloth's hair curves from its stomach to its back, which is the opposite direction of hair growth on most animals.

Speaking of hair, sloths have excellent camouflage (physical traits which help them to blend into their surroundings in order to hide from predators). Sloth hair is grey and brown so that it matches tree bark.

However, sloths often have a bluish-green appearance during rainy months because the extra moisture in the air allows algae to grow on their fur. Since the rainy season allows more leaves and moss to grow on the trees, having a bluish-green coat helps sloths to blend into their environment.

Little Lion Experiment:

Unlike most mammals, sloths allow their body temperature to fluctuate somewhat along with their environment. So, their bodies get colder at night and during the rainy season.

As a result, their digestion slows during these times. This is because their digestion processes are temperature-dependent. In other words, the warmer a sloth's body is, the faster it will digest food.

So, if sloths get cold enough, then they can not digest food quickly enough to survive. This means that sloths can actually starve in cold weather even if their stomachs are full of food!

To examine temperature-dependence, fill a Styrofoam cup with 2 inches of very cold water. Place a wooden toothpick into the water and leave it there for the rest of this experiment (it will reduce 'bubbling over' in the microwave).

See how much salt you can dissolve into the cold water. Remember, dissolved salt is invisible, so as soon as you see salt at the bottom of the cup, then stop adding salt! Intact salt means that you have dissolved all the salt you can at this temperature.

Microwave the cup for 10 seconds, then wait 15 seconds before opening the microwave door. Next, take the cup out of the microwave, carefully swirl it, then see if you can dissolve more salt into the water. Microwave for 10 seconds more, wait 15 seconds, and see if you can dissolve more salt. Note: do not repeat these steps again or else the water will become dangerously hot!

Do you notice a relationship between the temperature of the water and the amount of salt that can be dissolved in it?

What Are Honeycombs?

2005-06-15T13:55:00.000-07:00

When you think of honeybees, you probably think of honey. However, most of us don't give much thought to the honeycomb, also known as a wax comb. This comb is an array of hexagonal compartments in which larvae (baby bees) develop. A queen bee can lay up to 3,000 eggs per day, so there are always thousands and thousands of larvae that need compartments in which to grow!

If you've ever seen a honeycomb before, then you may have noticed that it is composed of tightly-packed hexagons. Bees use this shape because it has a small surface area (how big the walls are) compared to its large volume (3-dimensional space that it contains). In other words, hexagons "wall off" a lot of space using only a little bit of wax.

Another way to look at constructing a bee hive is that wax is what is "costs" the bees to build a hive. Bees have to spend time and energy making wax, so it's not a good idea to waste it. Compartments are what they get out of their work. Since there are so many larvae that need room to grow, space is precious, so wasting it is not an option for bees!

Therefore, bees want to build the largest number of compartments possible by using the least amount of wax. Getting a lot by using the least amount of material is called efficiency.

The most efficient shape for boxing in a single compartment is a circle. However, circles are not that efficient if you have to make more than one compartment. This is because having circles next to each other (like a bunch of cookies on a dish) means that there will always be wasted space between the circles.

So, bees use hexagonal compartments, which contain almost as much volume as circular ones, but which do not waste any space. In other words, if you arrange hexagons in the right way, then there will be no space between the compartments, which means no wasted space!

Honeybees have been around for over 150 million years, but still, how did they manage to figure all this out? Well, they weren't sitting around measuring the surface areas of different shapes. Rather, different groups of bees tried different ways of building honeycombs. The bees that built the most efficient honeycombs were able to give more of their larvae a place to grow. So, that's how bees evolved to make hexagonal honeycomb.

Little Lion Experiment:

Get some play-dough or clay and roll out three smooth sheets which are about 5' across. Then, roll out a long coil and flatten it so that it is about 1/8' thick, 1' wide, and exactly 2 feet long. Using a butter knife, slice off the rough edges to make a 2-foot-long rectangle. Use a ruler to make sure that all parts of the rectangle are equally wide!

Cut the rectangle into three 8' strips. Stand a strip on its edge and bend it around to make a square. Use the second strip to make a triangle. Use the third strip to make a hexagon. Remember, you used the same amount of clay to make each shape, so all three have the same surface area.

Connect each of your three shapes to a 5' sheet so that you have three boxes without lids. Use a tiny bit of extra play-dough or clay to seal the cracks. Put your boxes over some newspaper in case they leak. Make sure that the boxes are still level with the table!

Now, we're ready to measure the volume. Fill the hexagonal box with sugar. This volume of sugar is equal to the volume of the box.

Then, carefully pour the sugar from the first box into the second box. You'll have leftover sugar since the second box has a smaller volume than the first box does.

Next, use the sugar from the second box to fill the third box. Judging by the amount of sugar needed to fill the second box versus the third box, which one has the larger volume?

What Is Special About Dandelions?

2005-05-15T13:54:00.000-07:00

You've probably seen dandelions before: yellow flowers which turn into white fluffy spheres. But, despite these interesting flowers, the part of the plant that the dandelion is named after is actually the leaf! The sides of dandelion leaves have a zig-zag shape because they have very deep dents in them. This zig-zag shape reminded early Europeans of lion's teeth, so they called the plant "dent-de-lion," which means "lion's tooth" in Old French! The name "dent-de-lion" then became modernized into "dandelion."

Although dandelions originated in Europe, they were brought to many other regions of the world and now can be found virtually anywhere! This is because dandelions can survive and thrive in many different environments, including some that are harsh enough to kill most plants. In other words, the dandelion is one tough plant!

In fact, the toughness of dandelions makes them very hard to get rid of. If you simply pull off the leaves and flowers, the plant will regenerate (re-grow), much like a starfish can regenerate if it loses its limbs.

As for the flowers, they are actually composed of many tiny flowers arranged in a circular bunch, which is typically 1 to 2 inches wide. This is called a composite flower. In fact, each composite flower of a dandelion is made up of hundreds of tiny individual flowers! This explains why each composite flower can produce hundred of seeds (one per flower).

Another example of a composite flower is the sunflower. The difference (other than size) between sunflowers and dandelions is that the small flowers in the middle of a sunflower look like little buds. They are greenish-brown instead of yellow and do not look like they have petals. These central flowers are called disk flowers.

The outer flowers (the ones that are bright yellow) are called ray flowers. Dandelions are unique in that they are completely made up of ray flowers. In other words, they don't have any disk flowers. This is why all of the flowers in a dandelion look the same.

Another unique characteristic of dandelions is that they don't rely on insects to carry pollen from one flower to another. This process is called fertilization, or cross-pollination. In contrast to most plants, dandelions can fertilize themselves. This makes it even easier for them to reproduce, making them even better weeds!

Furthermore, the seeds have a unique way of spreading themselves around. You have probably noticed that dandelions become white and fluffy after they have bloomed. In fact, this transformation from the yellow composite flower to the white "snowball" form can occur overnight!

Later on, some of the "fluff" blows away in the wind. These fluffy pieces are actually dandelion seeds being carried by tiny white "parachutes" which float well in the wind. This helps the plant to spread its seeds over a large area, which makes it more likely that some will land in a nice patch of soil and be able to grow into new dandelion plants.

Little Lion Experiment:

To see just how effective these "parachutes" are, find a dandelion in its white fluffy form, and pull off the fluff. Pull slowly so that the seeds stay attached to the fluff! Then collect some similar-sized seeds (basil seeds work well for this). Now that you have two sets of seeds that are similar in size, shape, and weight, you can be relatively certain that any differences in how far the seeds travel will be due to the dandelion's parachute (rather than its size, shape, or weight).

Go outside on a windy day and toss the basil seeds up into the air. Watch them fall and notice how far (horizontally) they travel form where you are standing. Do the same with the dandelion seeds. Notice how much further they travel.

Now, can you see why dandelions sprout up in odd places such as cracks in the sidewalk? You don't see basil plants growing there! Seeds that travel far and wide are able to end up in environments much different than those in which they started. So, if you had a basil plant and a dandelion in a garden, where would you expect to find the next generation of basil plants? Where would you expect to find the next generation of dandelions?

What is Fool's Gold?

2005-04-15T13:52:00.000-07:00

You've probably heard of "fool's gold" before, but what exactly is it and how does it differ from real gold? The technical name for fool's gold is pyrite. Like real gold, it is brass-colored, hard, and shiny. However, it is not made out of gold, which is why it's not nearly as valuable.

Pieces of pyrite have jagged edges and can sometimes form cubes. Sometimes pyrite also has a grain (sets of lines, just like in wood). Pyrite can be found right here in Pennsylvania, but it is also located in other states, as well as in Mexico and Europe.

True gold is an element. Elements are the smallest building blocks of everything in the universe. They are made of positively-charged particles (protons), negatively-charged particles (electrons), and neutral (non-charged) particles called neutrons. The only difference between different elements is how many of each type of particle they contain.

Besides gold, some other elements that you may have heard of are: silver, iron, mercury, and oxygen. As you can see from that list, elements can be solids, liquids, or gases.

The smallest piece or unit of an element is called an atom. Atoms can combine with each other to form molecules. Some molecules (like oxygen) are just made up of one element. The oxygen that we breathe is written as O2, since there are 2 atoms of oxygen in each molecule, and the symbol for oxygen is O. In other words, oxygen atoms are floating around in the air in pairs.

In contrast to O2, most molecules are made up of two or more different elements. For example, you may have heard water referred to as "H2O." This means that each molecule of water contains 2 hydrogen (H) atoms and 1 oxygen (O) atom.

You might be wondering why we don't write water as H2O1. It is just a scientific custom to not write 1 when there is only 1 atom of a given element in the molecule. By the same token, you can think of your hand as Finger5Palm since each hand is made up of 5 fingers and one palm.

Make sense? Now let's apply what we just learned and figure out the symbol for fool's gold! In contrast to real gold, pyrite is made of the two elements iron and sulfur. The symbol for iron is "Fe" and the symbol for sulfur is "S." Each molecule of pyrite is made up of 1 atom of iron (Fe) and 2 atoms of sulfur (S). So, pyrite is written as FeS2. In case you were wondering, the symbol for real gold is Au.

Little Lion Experiment:

When pyrite mixes with acid rain, it dissociates (comes apart) so now the iron and sulfur are separated from each other and are no longer grouped into molecules of pyrite. When molecules dissociate, you can't see them anymore since they are broken up into such tiny pieces. So, the solutions (mixture) is clear.

When this solution mixes with groundwater (which isn't acidic), the iron can't remain in the solution and so it sinks to the bottom. But since it is exposed to water and air, it rusts. So, you are left with a rust-colored gel from the wet rusted iron. You may have seen this on rocks at the bottom of streams.

Most people don't have pyrite at home, so we're going to use antacids, which will behave the same way as pyrite does in this experiment. Ask your parents for an antacid tablet (like TUMS or Maalox). This experiment will be easier to see if the tablet is colored instead of white. If you don't have antacids, then ask for a calcium vitamin.

Break off a pea-sized piece, place it between two paper towels, then use a spoon to grind the tablet into a very fine powder. Put the powder into a cup. Add a teaspoon of water (this is like groundwater). Mix, and notice how the dust doesn't dissolve (you can still see it). To mimic acid rain, add a teaspoon of lemon juice (this is an acid). Mix, and see if some of the dust dissolves. The solution should become more transparent (see-through) since there is less powder floating on top.

How Are Rabbits And Hares Different?

2005-03-15T13:51:00.000-08:00

This month, you'll probably see a lot of Easter decorations around. So, let's have a look at what makes a rabbit a rabbit, and a hare a hare. Baby rabbits are born with their eyes closed and without a fur coat. Rabbits build nests in which to care for these very fragile newborns. In contrast, newborn hares are fully-developed (with open eyes and coats of fur). Hares do not build nests.

Sometimes common names can make the distinction between rabbits and hares a little fuzzy (or furry as the case may be!). For example, black-tailed hares and white-tailed hares are commonly called jack rabbits, even though they are actually hares (not rabbits). The snowshoe hare is commonly known as the snowshoe rabbit. Cottontailed rabbits, however, are actually rabbits.

So, how did the snowshoe hare get its name? The answer is that, in the winter, it grows very long fur over its feet, which makes them look like snowshoes. Just like snowshoes give people a wider base to walk on, the extra fur on the hare's feet gives them a wider base. This helps the hare run more easily through the snow by not getting bogged down as deeply in it. Rather, it glides over the surface of the snow as it runs.

As its name suggests, the snowshoe hare is completely white (except for the tips of its ears) in the winter, but the white-tailed hare can turn completely white too if it lives in a very cold environment. So, sometimes what seems like a snowshoe hare might actually be a white-tailed hare.

In the warmer months, the hares shed their white coats and replace them with grayish brown coats. This makes sense when you think about the forest when it is not covered in snow. If a hare is running through the forest, it is likely to be seen against tree trunks, dead leaves, and rocks. Since these items are brown and gray, the hare can blend in if it too is brown or gray.

Why does environment make a difference in fur color? The answer is that animals survive better if they can hide from their predators (animals that eat them). One common way to not be noticed is to blend into the background by matching it. In nature, this is called camouflage.

Let's think through why different fur colors correspond to different seasons. In very cold regions, the ground is often covered in snow. So, to blend in with its snowy environment, the snowshoe hare and the white-tailed hare grow white coats of fur. In contrast, warmer environments for the hares have darker backgrounds (like mountains and deserts). So, a brown or gray coat of fur is the best camouflage in these warmer areas.

Little Lion Experiment:

Animals don't decide what color to be; rather they have evolved (adapted over time) to have this camouflage. Basically, the animals that blended into their environments were able to hide from predators, so they survived much more often than those that didn't blend in well. As a result, the hares that survived were those who happened to make coats that matched their environments, while the animals that got caught by predators were usually the ones that "stuck out" and were therefore easier for predators to find. Over time, the only families of hares left were those who blended in with their environments.

You don't generally see many wild animals in the winter, but as the seasons change, you will see many more animals (like birds that had flown south for the winter) returning to this area for the warmer months. You will also see animals that stayed here, but did not leave their shelters very often during the winter. As you look around, try to spot other examples of camouflage in the animals that you see. Think about where those animals usually live (as opposed to where they are when you happen to see them) in order to see how their bodies blend into their environments.

How Do Animals Cope With The Winter?

2005-02-15T13:50:00.000-08:00

When you come inside after a walk in the snow, aren't you glad that you have a heater in your house? What would life be like without a heater? This challenge is faced by wild animals every winter.

It is very difficult to survive in the winter for two main reasons: the cold temperatures make it harder to stay warm, and there isn't as much food available (since most plants don't grow in the winter, and many animals migrate to warmer areas). So, animals either need to avoid the cold weather, or find ways to survive in it.

The most common strategy to survive the winter months is called hibernation, in which the animal goes into a deep sleep-like state until the weather becomes warmer. This allows the animal to avoid the cold weather without having to move to a warmer climate (like birds do when they migrate south for the winter).

Hibernation is more than just sleep. It is a way to conserve energy by slowing down all of the body's processes. The animal's body produces less heat so its body temperature gets colder, and the animal also breathes much more slowly. These two bodily changes, along with the fact that the animal isn't moving, allow it to use up much less energy than it does when it is awake.

This is important since animals get their energy from food, and obviously the animal is not eating any food while it is asleep! But if the animal doesn't eat while it hibernates, then how does it get energy? Hibernating animals eat enormous amounts of food right before they hibernate. This extra food energy gets stored as fat (bears can gain 40 pounds per week when they are preparing to hibernate!). Then, once asleep, their bodies use the extra fat for energy. Since the animals' bodies are in "slow mode" during hibernation, they do not require very much energy, and so the fat contains enough energy to sustain the animal through the winter.

Humans cannot hibernate, and so we need to eat every day, but hibernating animals are able to survive weeks or even months just by getting energy from their stored fat. Humans aren't the only animals that don't hibernate though. Grey squirrels, red foxes, and wild turkeys are just a few examples of other non-hibernators.

After you categorize an animal as a hibernator or non-hibernator, it is important to ask what type of hibernation it uses. This is because there are two kinds of hibernation: deep hibernation, and a more mild version called torpor. Deep hibernation is also called true hibernation since it is what we normally think of (sleeping through the whole winter without waking up) when we hear the word "hibernation." Examples of deep hibernators are: box turtles, toads, woodchucks, and garter snakes.

In contrast, when an animal is in torpor, it can wake up occasionally to look for food, then go back to sleep. In fact, some animals perform their normal activities during the day and just use torpor at night. In addition to being able to wake up easily, an animal in torpor has a higher body temperature (about 60F) than it would if it were in deep hibernation (around 41F, which is very close to the temperature of your refrigerator!). Black bears, skunks, and raccoons are examples of animals that use torpor during the winter.

Little Lion Experiment:

Get out a small pot and a thermometer that goes down to 40F (5C) or lower. If you don't have a thermometer like that, then put some cold water in the fridge, which is almost exactly the same temperature (41F) as a deep hibernating animal. Put a cup of warm water on the kitchen table. Let both cups sit for 20 minutes. Make some ice cubes (ask an adult if you need help).

Next, put an ice cube into the pot. Put the pot on the stove over low heat (get an adult to help you with this step). The ice cube will begin to melt into water. Keep checking the temperature of the water with your thermometer (or compare it to the refrigerated water) to see how long it takes for the water to reach 41F. We'll call this the "deep hibernator time." Also note how much longer it takes to heat up to 60F (the body temperature of an animal in torpor). We'll call this the "torpor time." If you don't have a thermometer, then you can just wait until the water is almost as warm as the room temperature water. Also record how much more time it takes to warm up to 98.6F, our body temperature (any household thermometer should be able to detect that temperature). We'll call this the "human time."

The amount of time it takes to reach a given temperature is directly related to the amount of energy (heat) that is needed to warm up the water to that temperature. So, the "deep hibernator time" shows how much energy is needed to go from freezing (which is about how cold it is where the animal is hibernating) to the animal's body temperature. Similarly, the "torpor time" shows how much energy is needed to go from freezing to that animal's body temperature, and the "human time" shows how much energy is needed to go from freezing to our body temperature. More importantly, the difference between the "human time" and one of the other times shows how much energy those animals are saving by only warming their bodies up to 41F or 60F instead of normal body temperature.

How Do Snowflakes Form?

2005-01-15T13:49:00.000-08:00

Snowflakes are a beautiful part of winter. You probably know that snow is a frozen version of rain, but why does snow fall in flakes rather than in drops? In other words, how do snowflakes form?

Like rain, snowflakes are formed in clouds (which are made of water vapor and tiny drops of liquid water). Since water freezes at 32 F, the water in clouds can freeze if the temperature is 32 F or below.

You may have noticed that snowflakes can have various shapes. Some look like typical intricate snowflakes (called dendrites), others look like long needles or tubes, while others look like hexagonal (six-sided) plates. If these plates have indentations (notches) in them, then they are called sector plates.

What determines the shape of snowflakes? The major factor is temperature, but snowflake shape is also affected by wind, humidity (how much water vapor is in the air), the amount of dust in the clouds, and the altitude (height) of the clouds.

These conditions are important because they determine how the water molecules (H2O) in a snowflake will be arranged. Whichever arrangement forms the most easily under a given set of conditions is the one that will happen in most of the snowflakes that day. This explains why, on a given day, most snowflakes look similar, but you can always find a few odd ones.

Since some conditions (such as wind currents) change so quickly, each snowflake is usually a tiny bit different than its neighbors. It is possible for two snowflakes to be identical, but this doesn't happen very often. Even if two snowflakes look identical, they are probably a tiny bit different. For example, one snowflake might have a few more water molecules in it than the other snowflake does, but your eyes can't see such a small difference.

As a general rule, there are five different snowflake shapes. Each one is found most commonly within a certain temperature range, as shown below:

Thin hexagonal plates	32-25 F
Needles	25-21 F
Hollow columns	21-14 F
Sector plates	14-10 F
Dendrites	10-3 F

Table adapted from http://chemistry.about.com/library/weekly/aa121001a.htm

Think about the first snowfall of the winter. It usually looks like hexagonal plates or needles. This makes sense since the first snow usually falls when the temperature outside has barely dropped below freezing. The prettiest snowflakes (dendrites) tend to fall in January and February since these months are the coldest.

Little Lion Experiment:

On a day when it is snowing, put a piece of black construction paper in the freezer for 15 minutes or more in order to chill it. Then, go outside and hold the piece of paper so that snowflakes land on it.

The black color of the paper should allow you to easily see the shapes of the white snowflakes. However, the paper may begin to warm up after a while. If the snowflakes are melting on the paper, then you can cool the paper down by simply setting it on the ground against some snow, or standing over it so that it lies in your shadow.

Examine the snowflake shapes and try to figure out which of the five major types you have in front of you (there may be more than one shape on the paper). Repeat this experiment on other days when it is snowing. Try to do it on days with different temperatures (like 10 F, 20 F, and 30 F) so that you can see the different snowflake shapes that form at various temperatures.

Why Is It Often Warmer On Cloudy Days?

2004-12-15T13:48:00.000-08:00

Why would clouds make it warmer outside? First we have to know what a cloud is made of. We see them all the time, we know rain comes from them, and we've probably pointed out some that look like animals or other shapes, but we may not know exactly how they are made.

It starts out when water from lakes, rivers, ponds, streams, and other water on the ground evaporates into the air. To say that the water evaporates means that some of the water leaves the ground after being heated by sunlight, and is carried by the air in very tiny droplets or as water vapor (gas) that cannot be seen with the naked eye.

You may have heard that warm air rises. The warm air close to the earth that carries the water vapor is an example of this. As the air rises, it cools, losing the heat that kept the water droplets suspended in the air. This cooling causes the water vapor to condense (turn back into liquid droplets). These droplets land on tiny specks of dust in the air. In other words, the water is no longer carried invisibly by the air, but instead, it clings to the dust particles. Groups of these wet particles make clouds.

How do clouds make it warmer outside if a cloud is only water droplets clinging to dust in the air? Actually, the clouds don't make it warmer outside; clouds keep it warmer outside.

A blanket of clouds covering the sky is a little like a blanket that you use to stay warm in the winter: the blanket holds in heat. Sunlight is the source of energy for the earth, and some of that energy is in the form of heat. On days when there are no clouds, heat from the sun can enter and leave the atmosphere without anything getting in the way. When it is cloudy, the clouds absorb (hold) some of the heat so it can't escape. Clouds also reflect some of the heat back towards the earth.

So, on a cloudy day, some energy from the sun gets into the atmosphere through the clouds, but can't get out again. When this happens, the heat builds up during the day, so it gets warmer outside. On days when there are only a few hours of daylight, the sun doesn't have much time to send some of its heat energy through the clouds, and not very much heat builds up. That's why, even on cloudy days, it's still cold out in the winter.

Sometimes it gets even warmer on cloudy days because of advection. Advection is the movement of heat, cold, and moisture when air moves (when there is wind). When warm air from a tropical climate moves into a cooler area on a cloudy day, the clouds keep in the heat just like they keep in the heat from the sun.

Since warm air can hold water vapor better than cooler air can, clouds that are very high up in the cooler part of the atmosphere do not have as much water, and so they are not as thick. Since thinner clouds let in more light and heat energy from the sun, it is not as warm on a day with high, thin clouds as it is on a day with a low, heavy cloud cover.

To summarize, clouds are made of droplets of water that cling to specks of dust in the air. Some heat energy from the sun can make it into the atmosphere through the clouds, but the clouds trap the heat in by reflecting and absorbing it, causing the air inside the cloud blanket to warm up throughout a cloudy day. Warm air moved by advection can bring heat into an area that will be held in if there are clouds. High, thin clouds do not hold in heat energy well as lower, thick clouds do.

Little Lion Experiment:

In order to see how clouds form on particles in the air, you will need:

black sheet of paper
glass jar or mug
flashlight
clear bag with ice
confectioner's sugar

Steps:

Tape a black sheet of paper to one side of a glass jar or mug.
Have an adult boil about a cup of water then fill the jar or mug part of the way with boiling water.
Immediately sprinkle a small amount of confectioner's sugar into the top of the jar.
Quickly cover the jar with the bag of ice. Turn out the lights and shine the flashlight into the jar.

You should be able to see a cloud forming inside of the jar as the warm water evaporates, rises, and condenses onto the particles of confectioner's sugar when it reaches the higher air cooled by the ice. You may also see the water condense directly onto the sides of the jar or mug instead of onto the particles, but keep in mind that there is no container for real clouds; only dust particles.

This experiment was adapted from Teacher.net Lesson Exchange; http://www.teachers.net/lessons/posts/14.html

How Do We Hear?

2004-11-15T13:47:00.000-08:00

There are so many diverse and interesting sounds in our daily lives that we tend to focus on the sounds themselves, but never really stop and think how we are able to hear them. What exactly is a sound anyway? In a nutshell, sounds are how our brain perceives waves that enter our ears.

Believe it or not, there is nothing inherently noisy about sound waves! The waves are the result of vibrations. For example, when you pluck a guitar string, it vibrates at a certain frequency (frequency is basically how quickly something vibrates). This causes the air around the guitar to get compressed (pushed together) in some areas, while the other areas expand.

Why does this happen? First, keep in mind is that, even though we can't see them, there are billions of molecules (tiny particles) floating around in air. Now, if you carefully watch a guitar string, you can see it go up and down very quickly when you pluck it. So when the string is moving towards you, it bangs into the air molecules and pushes them forward (thus compressing them). When the string moves away from you, it allows the air to expand. This pattern continues as the string vibrates, so you get alternating areas of compressed, expanded, compressed, expanded, etc.

This is like waving your hand in a pool of water. You hand moves at a much slower frequency than a guitar string, but it is a vibration nonetheless. If you've ever done that, then you know how difficult it is to move because your body spends so much energy pushing the water molecules out of the way.

You may have also noticed that waves ripple outwards. This is because the water near your hand gets pushed forward when your hand moves toward it, and it is allowed to expand when your hand moves away from it. The water waves that occur when your hand vibrates in water are similar to sound waves rippling outwards when something vibrates in air.

So, now that we understand what sound waves are, we can see that sound itself is not a result of plucking a string, banging a drum, etc. Only the waves are what result from those vibrations. Sound is just how our brain interprets those waves. It categorizes them according to their frequency, with high frequency (fast waves) sounding high-pitched like a violin, and low frequency (slow waves) sounding low-pitched like a bass.

When sound waves enter our ears, they cause bones in the ear to vibrate. Then those bones cause the fluid that lies in our inner ear to vibrate (like when you wave your hand in water).

Our inner ear also contains many tiny hairs along its surface. Each hair is programmed to respond to a certain frequency of waves in the ear fluid. When specific hairs come in contact with their "favorite" frequency, they send messages to the brain so it will know that that particular frequency has just entered the ear. These signals are interpreted as pitch. How is this amazing sensitivity achieved?

Our hair cells are basically arranged in a line. Each frequency "peaks" (is most intense) at a certain hair cell location, so each hair cell can respond to the one and only one frequency: the one which peaks where that hair cell is!

High frequencies tend to fizzle out quickly, so they only reach the hair cells that are close to the outside world. So, it should be no surprise that these hair cells respond to high frequencies. Low frequencies travel much further and "peak" further inside of your head. So your innermost hair cells are programmed to respond to low frequencies.

So, the lower a sound, the further inwards it peaked in your inner ear. The higher a sound, the further outwards it peaked.

Little Lion Experiment:

Stretch a rubber band around your thumb and index finger. Pluck the rubber band and notice the pitch. Stretch the rubber band by moving your thumb away from your index finger. What happens to the pitch now? Can you guess if the frequency is higher or lower?

After your pluck it, the band will keep vibrating but it won't move as far up or down (the height of the movement is called amplitude, and it corresponds to loudness). The frequency, however, shouldn't change (be careful not to move your fingers though!). If the frequency does change, then the pitch will change since frequency is interpreted by your brain as pitch. So, you can observe the frequency just by listening to see if the pitch changes over time! That allows you to see that the frequency stays the same even though the amplitude decreases.

Why Doesn't Candy Spoil?

2004-10-15T13:46:00.000-07:00

It's that time again.. Happy Halloween everyone! With all those sweets, it's a good thing we don't have to fit them all in the refrigerator! Since we have to keep most of our food cold in order to prevent it from spoiling (you wouldn't want to leave milk out on the table all day!), then why don't we have to refrigerate candy?

First, let's look at why food spoils. For the most part, it is due to the growth of bacteria (microscopic life forms, each made of one cell). Bacteria naturally exist on everyone and everything, including food. Most of these bacteria are harmless, which is why we don't get sick from eating food in general. But, if bacteria are allowed to grow out of control then our food can become rotten.

Now, the question is: why can't bacteria grow effectively on candy? The answer is that there is too much sugar for them. Most bacteria need a small amount of sugar in order to survive, but if they are surrounded by too much of it, then they begin to dry out like raisins. This is because water flows toward a state of equilibrium (balance). The technical term for this is osmosis (pronounced "oz-MOSE-iss"). Water reaches equilibrium between the cell and its surroundings when the same number of molecules is dissolved in each place (dissolved substances are called solutes). The reason for this is that solutes take up space, so there is less room for water in the mixture. Water then flows by osmosis to make up for this difference.

Cells contain a lot of water, but there are also plenty of solutes in the cell. If there is an equal amount of solute inside of the cell as outside of it, then water is already in equilibrium. This is called being in an isotonic environment.

If there are more solutes outside of the cell, then that means less water, so water will leave the cell, and so the bacteria will become shriveled and die. The term for this is a hypertonic environment.

If, on the other hand, there are less solutes outside the cell, then there is more water outside, so water will flow into the cell, which can cause it to swell or even burst. This is called a hypotonic environment.

Bacteria have ways of dealing with slightly hypertonic or hypotonic environments, but most cannot deal with extreme situations, and so they shrivel up when they are surrounded by too much sugar or salt. This is why people used to salt their fish before refrigerators were invented. [Safety note: wet sugary foods (like an open jar of jelly) do need to be refrigerated, so don't stop storing food in the refrigerator or else some fungi, which are not bacteria, could grow in it at room temperature!]

Little Lion Experiment:

Bacteria are not unique in their responses to osmosis, but there are some differences among other types of cells. For example, all cells can become dried out, but plant cells like hypotonic environments more because the inward flow of water helps their cells to remain rigid, which is why healthy flowers don't wilt.

To see the effects of osmosis on plant cells, take a grape and cut it in half. If possible, peel the skin off of each half. Obviously, the halves would line up if you were to put them back together right now. Next, totally cover one half of the grape with sugar, and put the other half in some water. Leave them sit for five minutes, mixing the sugar once in a while so the grape is always touching dry sugar. Thought question: why did the sugar touching the grape get wet?

Which situation is hypertonic, and which is hypotonic? Knowing what you know about how plant cells respond to osmosis, which half do you think will shrink? After five minutes, take the grape half out of the water and put it on a napkin. Brush the sugar off of the other half (DON'T rinse it, or else you will be soaking it in water!!!). Line up the two halves to see if your predictions were correct.

How Does Memory Work?

2004-09-15T13:46:00.000-07:00

As we start the school year, we are going to learn many new things. We may forget some of that information after a short period of time, but we will remember some of it for years after we learn it. Have you ever wondered why certain memories stay with you for years, while some memories fade away after only a few minutes or hours?

Think of a few events in your life that happened years ago. Your mind probably conjured up something that was relatively significant to you either because it was an important day in your life (like a birthday or holiday), or something to which have an emotional attachment (like a big surprise or an embarrassing moment). You are able to remember these events so long after they occurred because they are stored in your long-term memory.

However, some information is stored only in short-term memory. These are things which we need to know for only a short time after we first learn them. For example, when you look up a new phone number in the telephone book, you can usually remember it long enough to walk over to your phone and dial the number. However, you probably wouldn't remember the number a day later. Saying something over and over in your head, or reading it many times reinforces the items in your short-term memory, and this is how studying for school works.

There is another type of memory called sensory memory, which involves remembering how something looks, sounds, tastes, smells, or feels. This is how most memories start out, but this type of memory can only be stored for less than a second unless it is quickly stored in short-term memory. Sounds and images are transferred most effectively, so if you hear the word "pizza," then the image which comes to mind is much sharper and clearly-defined than the vague (general) memory of how it tastes or smells.

Short and long-term memory involve different processes in the brain, but they are connected and they do interact. For example, the long-term memories that you recalled a moment ago are still fresh in your mind. This is another way of saying that they have temporarily been retrieved to your short-term memory.

Similarly, short-term memories can be stored as long-term memories if they are repeated or rehearsed enough over a long period of time. Taking our phone number example one step further, you know your own telephone number and maybe your best friend's number very well. This is because you have said, written, or dialed them so many times that they were eventually converted into long-term memory.

It is important to note that neither type of memory is perfect. This is why we forget things. In the case of long-term memory, when something is no longer significant, it may begin to fade. So if you move to a different house and get a new phone number, then you might forget your old phone number in a few months since you haven't used it recently. Long-term memory loss can also occur in old age.

Short-term memory loss usually occurs after a piece of information is no longer being reinforced by repetition or use. Also, most people can only store about 7 items at a time in their short-term memory, so "out with the old; in with the new" would be an appropriate way to look at it.

Little Lion Experiment:

Different people learn in different ways. Some are better at recalling images (visual learning), while others are more skilled at remembering sounds (auditory learning). Still others "remember by doing" (haptic learning). Almost everyone uses a combination of the above three methods, but most people lean more heavily towards one of them. To determine which of these memory categories best suits you, go here, scroll down a few paragraphs to the test section, and take the memory test. After you add up the totals for each of the three sections, you can figure out which type of memory you use the most (the higher the number, the more inclined you are to learn in that particular way).

What Is Special About The Octopus?

2004-08-15T13:45:00.000-07:00

Eight arms, no ears, blue blood, rows of suction cups...this is beginning to sound like a science fiction movie, but in fact, we're talking about the octopus! Octopi (the word for more than one octopus) live in oceans all around the world but are generally found in warmer climates. They can range from 3/8 of an inch (the Californian octopus) to 23 feet (the Giant octopus)!

Octopi from different species (types) vary in appearance, but they share the same basic body layout: they have eight arms (each has two rows of suction cups), a head (with two large eyes, a mouth and a very advanced brain), and a mantle, which is the large soft sac attached to their head. Although the mantle hangs off of the head, it can be thought of as the torso of the octopus because it contains so many vital organs like the heart, a digestive system, and gills.

As you may know, an octopus uses the suctions cups (called "suckers") on its arms to grab onto prey, but they also allow the octopus to smell and taste its environment. Imagine if you could taste and smell whatever you held in your hands as soon as you picked it up...an octopus can!

An octopus can also be thought of as an aquatic chameleon because it can change the color of its skin. This is done to express emotion, or for camouflage (pronounced "CAM-o-flaj"), which means blending into its environment so it will be harder for a predator to see it. Octopi can also change the texture of their skin for camouflage purposes.

Scientists continue to discover new and exciting facts about octopi, but this is a difficult task since they tend to be rather shy creatures. In fact, an octopus spends most of its life in crevices, holes, and other hiding places. It does this in part to protect itself from predators.

If the octopus is attacked, it has a few defenses to save itself from being eaten. The mantle of an octopus produces ink (like a squid, which is a relative of the octopus). When threatened, the octopus squirts ink at the predator. This blocks the predator's view of the octopus as it escapes. In some cases, the ink also damages the predator's senses so it can't find the octopus as easily.

Like a squid, an octopus doesn't technically swim away; instead it moves by jet propulsion. It does this by squirting water behind it from an opening in its mantle. The force of the water leaving the mantle pushes the octopus forward. The octopus then takes in more water and repeats this process so that it sprints forward in starts and stops.

Octopi hunt by attaching some of their suckers to their prey (a crab, for example). They then use their beak to make a small hole in the shell of the prey. Afterwards, they inject a poison to kill and partially digest the animal before sucking it out to eat it. There are over 100 species of octopi but only a few are poisonous to humans.

Little Lion Experiment:

When a 3-pound octopus uses its suckers to grab onto its prey, it would take 40 pounds of force to pull the two animals apart! This amazing strength is due to the large number (about 2000) of suckers on an octopus, as well as the properties of suction cups.

When you push down on a suction cup, air is squeezed out, which creates a vacuum. The tiny amount of air left inside can't generate much outward force, but there is plenty of air outside to push inwards (this is called "atmospheric pressure"). This imbalance of the two forces is what makes it hard to pull a suction cup off of an object.

To explore this topic, obtain a small suction cup with a hook on the end (like the ones used to hang up pictures). Attach it to the bottom of a glass table or another very smooth surface [rough surfaces won't work since the texture will allow air to leak in]. Hang weights from the hook until the suction cup finally falls off. The total weight of all the things you hung from the hook equals the amount of force needed to separate that one suction cup. Now imagine having 2000 of those!

Why Do Your Ears Pop On An Airplane?

2004-06-15T13:44:00.000-07:00

The human ear consists of the outer ear, your middle ear, and your inner ear which is fairly deep inside of your head. The middle ear is separated from the outer ear by the eardrum (or "tympanic membrane" in medical terms). So, the air trapped inside the middle ear doesn't come in contact with the air outside of your head. When you experience a change in air pressure by getting closer to or further from the ground, your ears will occasionally "pop" to adjust the pressure of the air that is caught in your middle ear so that it matches the air pressure outside of your head. This is done by quickly opening the Eustachian tubes (which connect the middle ear to the back of the nose) in order to let air rush in or out of the middle ear as needed.

Some people may find the popping of their ears to be annoying, but if your body didn't do this, then the pressure on one side of the eardrum would be higher than on the other side which could bend your eardrum slightly and compromise your hearing.

Little Lion Experiment:

To see the effects of having a blocked Eustachian tube, obtain a small plastic cup and a bowl with a flat bottom. If possible, use a clear cup so the water will be easier to see. If you don't have a clear cup, then try adding food dye to the water in this experiment to it will be easier to see once it is inside of the cup. Fill the bowl with about an inch of water. Turn the empty plastic cup upside-down and squeeze it until it bends inwards. Place the bent cup in the water.

Being careful not to let the lip of the cup rise above the water level, slowly squeeze the creases in the cup outwards so that the cup returns to its original shape. By doing this, you are creating a small vacuum. So, the pressure inside the cup (which pushes outwards) is lower than the pressure outside of the cup (which pushes inwards), and this pressure difference is what pushes the water from the bowl into the cup until the two pressures are equalized.

As a side note, the same principles of air pressure explain how straws, turkey basters and a variety of other objects are able to move liquids against gravity.

How Can I Avoid Getting A Sunburn?

2004-05-15T13:43:00.000-07:00

On most days, we do not get exposed to enough sunlight to cause us to develop a suntan. However, a nice day spent at the beach is much different. The darker your skin is, the more light you can withstand without having to boost your melanin production. When your body senses that you need more melanin to protect you against harmful UV rays, your melanocytes kick into high gear and you get a suntan. However, if you stay outside for too long, especially without sunscreen, then your body can't make melanin fast enough to keep up with the amount of UV exposure. This is what causes a sunburn. A sunburn can be thought of as a "clean-up crew" of various blood cells being sent to repair the damaged area. This increased blood flow is what causes sunburns to appear red and feel warm to the touch. Starting to sound a bit like a sunburn? There's one thing missing: why does sunburned skin tend to peel? Your body does its best to repair the UV damage, but if the damage is too great, then the unrepaired cells will simply flake off to make room for new healthy cells to replace them, which allows the sunburn to heal.

You may have heard about the relationship between sunburns and skin cancer. Even though the "clean-up crew" and the skin cells themselves usually undo the harmful effects of UV, they may not always do a perfect job. This would allow damaged cells to stay in the skin. Most sunburns will not lead to cancer, but a tiny fraction of them can if they damage a cell's ability to stop dividing. This is why it is so important to wear sunscreen in order to avoid over-exposure to UV light.

There are two types of sunscreens: those that reflect UV light (like tiny mirrors) and those that absorb it like melanin does. Everyone gains extra protection from wearing sunscreen, but if you are fair-skinned or albino, it is especially important that you wear it. Remember to put it on around 30 minutes before you go outside so that it has time to stick to your skin. Otherwise, it will rub off on the grass or wash off in the water. [Safety note: some people (especially those with sensitive skin) have allergies to PABA, a chemical in some sunscreens. So if you have sensitive skin, you may want to consider buying a PABA-free sunscreen].

For more information, visit http://travel.howstuffworks.com/sunscreen.htm

Little Lion Experiment:

What Are Allergies

2004-04-15T13:42:00.000-07:00

A-choo! Here comes another day of living with allergies. We are all familiar with the coughing and sneezing, but what exactly are allergies and what causes them?

Every day, our bodies are in constant contact with potential threats. These include pathogens (harmful microorganisms), pollution, and a host of other dangers. However, most of the time, we aren't even aware that anything nasty has entered our bodies. How are we able to combat these invaders so effectively? We have our immune system to thank. Immune cells called lymphocytes (pronounced lim-fo-sites) patrol all parts of the body looking for foreign molecules and microorganisms (tiny living things, like bacteria). Each lymphocyte is programmed to recognize a specific pathogen. Anything which is not part of our body is classified as "non-self" while every one of our own cells is termed "self." In short, the role of the immune system is to attack and destroy any cells it finds which are "non-self."

We also have sensors in our bodies which can detect the presence of harmful chemicals. Have you ever walked by a car and coughed or sneezed as you smelled the exhaust? This is because you have sensors in your nose, throat, and lungs that tell your brain that you have inhaled dangerous fumes, which you need to get rid of right away. So, your body sends the signal to cough and sneeze until you push out all of the fumes. This signal is sent by a chemical messenger called histamine.

If you have allergies, or know someone who does, then you might agree that the symptoms of allergies are kind of like a huge overreaction to the car fumes, except without the car! People with allergies react as if they have inhaled something toxic when in fact they have just inhaled normal everyday things like pollen and dust that are not harmful (these everyday substances are called allergens). This occurs because some of their lymphocytes are programmed to recognize the allergen as a harmful substance even though it is not. So, when the lymphocytes find an allergen floating around in your body, they trigger histamine to be released which causes the common allergic symptoms such as watery eyes, runny nose, sneezing and coughing (these are all ways to flush out the allergen). Histamine also triggers local swelling near the pathogen or allergen, and so it can cause narrowing of the airways (nose and throat) when you inhale pollen or dust in order to prevent more of the allergen from entering the lungs. Unfortunately, that makes it harder for the person to breathe (fun fact: histamine is also responsible for asthma - can you see the connection?).

So how can we treat allergies? The primary method to prevent allergic symptoms is to treat the person with antihistamines, which have been used since the 1930s to control allergies. The medicine does not affect the lymphocytes, but rather it just prevents histamine from triggering its bothersome symptoms.

Little Lion Experiment:

Obtain an empty toilet paper roll. Run water from your sink over the inner surface of the roll until it is wet but not soggy. Then, make 4 small piles (one of each) of the following: black pepper, confectioner's sugar, salt, and jimmies (sprinkles). Hold the tube sideways in one hand over the sink (so as not to make a mess). One at a time, put a pile in your hand, then carefully place it on the inside of the tube, then rotate the tube until it is coated with the substance. If the substance does not stick, then that is a pretty good indication that it is large enough that it would not stick to the lining of your nose or throat. If it sticks, then it is probably something that would get trapped in your airways if you were to inhale it. Slowly turn the tube until it is vertical. To simulate coughing, quickly shake the tube or bang it against the inside of your sink. See which kinds of substances come out the most easily. To simulate sneezing, blow air through the tube and see what comes out in your sink. The body also uses mucus in your airways to help carry foreign molecules out (like the sea carries shells to the shore). Pour a small amount of oil into the tube and see if it takes out some of the remaining particles

How Does Shampoo Work?

2004-03-15T13:41:00.000-08:00

Have you ever wondered while rubbing shampoo into your hair how this colorful, sometimes clear soapy substance can clean hair?

Shampoo is made up of molecules such as ammonium lauryl sulfate that bond with the dirt and sweat on your hair. This bonding action helps shampoo clean your hair of dirt. Water helps by adding pressure to the shampoo-dirt components and rinsing these components out of your hair and down the drain.

Okay, so these shampoo molecules bond with dirt. How? Well, in the case of ammonium lauryl sulfate, the chemical detergent is similar to the dishwashing or laundry detergent used to wash dishes or clothes. Ammonium lauryl sulfate is a harsh chemical as it needs to bond aggressively with the dirt on your hair to clean it. Sodium laureth sulfate is also a detergent found in shampoos, but it is a little gentler to hair. Guar hydroxypropyltrimonium chloride is another type of chemical found in shampoos that adds volume and smoothes hair. This chemical helps make your hair easy to comb. Diethicone helps soften hair by coating the outer hair surface.

Shampoo is not just chemicals. It is actually 80 to 90% water. But, just using water won't really leave your hair clean, soft or comb-able. Rather, it is the 2 to 8% of detergents such as the chemicals listed above that really do the critical work of shampoo. The remaining 1% of shampoo is added fragrances or scents. The type of fragrance or scent your shampoo has really doesn't affect how clean your hair is, but it does affect the scent you smell when you are washing and brushing your hair.

So, shampoo helps clean hair; does it matter how much is used? The amount of shampoo should be about the size of a quarter. Anything less will not be enough to bond to all the dirt and sweat in your hair. Anything more is just wasting shampoo, water and your time. Too much shampoo can also leave your hair feeling dull as you wash away vital nutrients from your hair if you overwash it. Using a little more than a quarter may be necessary, though, if you were outside playing in a muddy creek.

One good way to tell if you are using too much shampoo is the amount of lather produced. Lather forms when the shampoo gathers around air instead of the oil from your hair. Dirt and oil actually destroy lather. If you have too much lather, you used too much shampoo. Remember, shampoo is to clean your hair, not the air.

Little Lion Experiment:

Materials:

A piece of polystyrene clear plastic
A soda straw to use as a dropper
A little shampoo
A centimeter ruler
A toothpick, wire or some other small diameter "stick-like tool" that you can coat with shampoo

Steps:

Place your polystyrene sheet on a flat level surface where you can observe easily from the side and from the top.
Place some drops of water on the sheet using your straw. You can do this by sticking your straw into a glass of water, placing your index finger over the hole and pulling out the straw. When you loosen your index finger slightly, you can control the amount of water that you drop out. Make some big drops and some small ones.
Measure the diameters of the drops and looking from the side, sighting with your ruler, estimate their height. Finally, and again looking from the side, estimate the angle at which the water contacts the polystyrene. Why are these drops all circular? Make a plot of the height versus the diameter? What do you conclude? Make a plot of the contact angle versus the diameter. Again, what do you conclude?
Take your "tool" (no shampoo yet), and push it across and through a water drop (i.e. move it parallel to the polystyrene). Describe what happens. You may want to try it several times to check what things happen every time.
Dip your "tool" in your shampoo and shake off the excess (we do not want any big drops). Now push your "tool" into the edge of one of the water drops. What happens? Now push it across and through a drop. What happens? How is this different from what happened before you dipped it into the shampoo?

This experiment was described by the Science and Technology Center, University of Texas at Austin.

What Makes a Rainbow?

2004-02-15T13:40:00.000-08:00

We have all seen beautiful rainbows across the sky after rain. But how does a rainbow form? Rainbows are usually formed when sky is full of clouds and it is about to rain. In order for a rainbow to form, we need two things, rain and sun.

When we look at sunlight most of us think of it as just one color: white, clear or blue. Sunlight is actually made up of all colors of light. All colors, which we see in rainbow, are originally there in sunlight. However, we do not see them in sunlight because they are mixed together. In the same way, if you take blue and yellow paint and mix them on paper you will see green paint. This green paint, as you know, contains both blue and yellow color; however, you only see green. Sunlight is the same way: when you mix all the colors of light together you get white light or sunlight.

Now that we know so much about light, let's look at what else make rainbows: rain. Rain comes from clouds. Clouds in the sky contain millions and millions of tiny raindrops. Rainbows are caused by the bending of sunlight as it passes through the raindrops. The raindrops act like miniature prisms. As white light enters the prism, it is separated into the individual colors of light. Both prisms and raindrops separate light based on the wavelength of the light. Light moves in waves, just like the waves in the ocean, and each color has a different length of wave. The longer the wavelength the slower the light color moves, purple is the fastest light and red is the slowest. The spectrum, or band of colors which make up the "white light" leaves the prism as separate bands of color. The more slowly a wavelength of light travels, the more it is bent by the prism. That is why the colors seen in the rainbow are always in the order red, orange, yellow, green, blue, indigo, and violet. The red light travels more slowly than violet light so it is bent more.

What Makes Soda Pop?

2004-01-15T13:40:00.000-08:00

Pop, soda or soda-pop bubbles and fizzes because of the gas called carbon dioxide (di-ox-ide). Carbon dioxide is same gas that we breathe out (We breathe oxygen in). When soda-pop is made a whole lot of carbon dioxide is pushed into a pop can. The can is then sealed and pressure inside the can is created. The pressure inside the can is higher than the pressure outside the can. This is why the can will "pop" when you open it. The amount of carbon dioxide that the liquid soda-pop can hold depends on the temperature and pressure of the liquid. The amount of a gas that a liquid can hold is called the solubility (sol-u-bil-ity) of the gas. The "pop" at the opening is caused by carbon dioxide being released from the liquid soda-pop since the amount of gas the liquid soda-pop can hold is changed when the pressure is changed.

If you take a soda-pop right out of the refrigerator and open it up, less carbon dioxide will be given off than if you opened it after it was sitting in the sun for hours. If you lower the temperature of the soda-pop the solubility of the carbon dioxide is increased, so more gas will stay in the liquid soda-pop.

Little Lions Experiment:

See if the laws of solubility hold true. Take a can of soda-pop that has been in the freezer for an hour or two, until it is cold, but not frozen. Wash out a styrofoam cup and lid from a gas-station or a fast food place, take a straw and put it in the cup. Tape around the opening in the lid where the straw goes. Take a second straw and insert in the straw from the cup and tape any joints between the straws. Insert the far end of the straw in a clear glass with water in it. You want to try to prevent any gas from leaving the cup, other than what goes through the straw to the water. Take the styrofam cup and fill it with your soda-pop. Close the lid quickly to prevent any escaping of gas. Place the cup in warm to hot water. Do not boil water with the cup in the pan or the cup will melt. Notice the carbon dioxide bubbling in the water. Does the amount of carbon dioxide given off change when you put the cup in the warm water?
Find hidden gases! Look around the house for other gas hiding in liquids. Some of these imposters are hydrogen peroxide, bleach, ammonia, perfume, and cologne. Notice how some of these hidden gases smell, and some smell bad! This is because gas molecules move around a whole lot more then liquid molecules, so our nose picks them up better.

How Was Ice Cream Developed?

2003-12-15T13:39:00.000-08:00

You know your favorite flavor and that you have to eat it fast before it melts, but do you know the science of ice cream? Believe it or not, ice cream as we know it has had a pretty rocky road in order to be as yummy and available as it is today. In "The History of Ice Cream," written by the International Association of Ice Cream Manufacturers (IAICM), Washington DC, 1978, a very detailed history of the cold and creamy treat is described. The funny part about the book, though is that most of the early history of ice cream remains unproven folklore.

And so the story goes...once upon a time, hundreds of years ago, Charles I of England hosted a banquet for many of his friends and family. The meal featured the greatest foods of the day and ended with a cold treat that resembled fresh-fallen snow. The guests as well as Charles loved the cold treat and Charles paid the cook 500 pounds a year to only serve it at his Royal table. The cook kept the secret until Charles was beheaded in 1649.

This tale along with others provides some insight into the evolution of our country's most popular dessert. Most likely, ice cream was not invented, but rather came to be over years of similar efforts. Even the Roman Emperor Caesar is said to have sent slaves to the mountains to bring snow and ice to cool and freeze the fruit drinks he was so fond of. Centuries later, the Italian Marco Polo returned from his famous journey to the Far East with a recipe for making water ices resembling modern day sherbets.

These tales are interesting and help to connect history with food science as well as cultural traditions. Unfortunately, no real historical evidence supports any of these stories. The tales might just have been a marketing plan of the nineteenth-century ice-cream makers and vendors. When it comes to actual facts, it seems that ice cream may have had its first appearance in China.

Although the actual history of ice cream is rocky, some of the inventions that were made to improve ice cream are a little more know. The first improvement in the manufacture of ice cream (from the handmade way in a large bowl) was given to us by a New Jersey woman, Nancy Johnson. In 1846, she invented the hand-cranked freezer. This device is still familiar to many. By turning the freezer handle, they agitated a container of ice cream mix in a bed of salt and ice until the mix was frozen. Because Nancy Johnson lacked the foresight to have her invention patented, her name does not appear on the patent records. A similar type of freezer was, however, patented on May 30, 1848, by a Mr. Young who at least had the courtesy to call it the "Johnson Patent Ice Cream Freezer." Commercial production was begun in North America in Baltimore, Maryland, 1851, by Mr. Jacob Fussell, now known as the father of the American ice cream industry. Right in our backyard at Penn State, tremendous research on how to make ice cream from making the best flavors to extending its shelf-life have been occurring for decades. Besides several tasty flavors, the Penn State Creamery offers a course (Ben and Jerry even took it) and a little museum. Maybe one day this summer when you are hot and in the mood for a sweet taste and a food science lesson you should ask your parents to take you down 322 E to Happy Valley. In the meantime, share your secrets on ice cream to your friends and family.

Little Lions Experiment:

Fill up a paper Dixie cup with water and another one with fruit juice. Only fill up the cups to about 3/4 full as liquid expands as it freezes (molecules in ice are bigger than they are in a liquid state). Then, place them carefully in the freezer and time how long they take to freeze. Monitor the process and see where ice forms first. Try to think why ice forms on the top before in the middle. Then, time to see which freezes first water or fruit juice. You can freeze other liquids such as milk or solids just as pudding or yogurt, if you want. Try to determine if a substance's state (liquid or solid) affects its freezing time as well as the material's density, i.e. has more sugar, food ingredients in it. Then, enjoy your frozen treats. Be careful, not to give yourself a "brain-freeze" as cold foods can cause mild nerve triggers that can hurt your head.

How Do Firecrackers Work?

2003-11-15T13:39:00.000-08:00

I am sure by this time of you most of you have seen, heard and even fired firecrackers. But, do any of you know what makes firecrackers crack, bang, and light up? If not, I will explain it to you. It is actually quite simple--it's science.

Today's firecrackers use gunpowder. But, firecrackers came long before gunpowder. The actually date centuries across to China. In fact, the firecrackers were entirely natural or organic. They were probably an accident, too. It is said that these early firecrackers came about because someone tending a fire ran short of fuel and decided to throw in a few lengths of green bamboo. Bamboo is a type of plant. The bamboo, knobby round reeds, would blacken, smoldered, and hissed. Surprisingly, they would end up exploding. How did this happen?

The answer is that inside bamboos are pockets of air and sap. These pockets, when weakened by the fire, will expand and eventually burst. The result is a sharp reverberating bang. Back then, this never-before-heard noise was quite alarming.

The Chinese figured that if this noise scared them it would scare evil spirits. One particular evil spirit was Nian. This spirit was known to eat crops and people! To protect themselves, the Chinese would use "bursting bamboo" or pao chuk at all special ceremonies such as weddings and celebrations for centuries.

Soon, a Chinese chemist accidentally discovered gunpowder. This chemist was mixing around sulfur, charcoal and potassium nitrate (KNO3) and BANG! This bang was more powerful and louder than ever!

Over time, the Chinese used chemistry to perfect their firecrackers. They also used this knowledge to do more than just scare evil spirits. They used firecrackers and extensions of them---rockets and bombs---to blow away their enemy.

Luckily, many scientists have stayed true to making firecrackers fun! These scientists have found that certain chemicals make the firecrackers colorful. And, potassium chloride (KClO3) was found to be even better than KNO3 as it made the colors deeper and brighter. Example chemicals that make certain colors are strontium to make red, barium to make green, copper to make blue, and sodium to make yellow.

Little Lion Experiment:

How to make safe firecrackers:

Materials:

Toilet paper or paper towel rolls
Dry rice or dry beans
Colorful wrapping paper
Curling ribbon

Steps:

Cover the cardboard rolls with wrapping paper. Leave about 3 inches of excess paper on each end. Gently twist wrapping paper to close ends. Secure the ends of the wrapping paper with ribbon. Before securing last end, put a few dried beans or rice inside. Shake the roll. It will make noise like a "firecracker."

Why do the Seasons Change?

2003-10-15T13:37:00.000-07:00

When does summer actually start? Do you think summer starts as soon as school ends? Or, do you think it starts as soon as the sun is out and burns your skin? The last day of school, sunny days and sunburns are all signs of summer. But, in the northern hemisphere (the top half of the globe), summer does not actually start until June 21st.

To be exact, summer starts at 0148 UT on June 21st, which is 9:48 Eastern Standard Time (our time zone) on June 20th. Yes, that means summer actually starts during the night of the 20th for us. But, June 21st is still the first full day of summer. Known as the summer solstice (sun stands still), June 21st is the longest day of the year.

In the southern hemisphere, below the equator (the line in the middle of the globe that splits the world into two), winter arrives. For them, June 21st will be the shortest day of the year. It also marks the start of winter for them.

Why do the weather and seasons change? To answer this question we have to think about the planet we live on. The Earth takes a yearly trip around the Sun. For part of the year, the Earth's north pole points away from the Sun and part of the time toward it. When the North Pole points toward the Sun, the Sun's rays hit the northern half of the world more directly and it is summer. But when the North Pole is pointed toward the Sun, the South Pole is pointed away. So the Sun's light hits the Earth at a less direct angle, spreading the warmth over a larger area, and it is winter.

Some people think the seasons are caused by how far the Earth is from the Sun. But, the Earth's orbit about the Sun is very close to circular and the distance of the Earth from the Sun only differs by about 3% during the year. Another problem with this hypothesis is we are actually closest to the Sun on about January 2nd, and the farthest on about July 4th. This is the opposite of hot and cold weather in the northern hemisphere. Therefore, the angle at which sunlight hits the Earth is more of a cause of seasonal changes than the Sun's difference from Earth.

Another factor in seasonal changes is the length of days and nights. In the summer, daylight lasts longer and nighttime is shorter. This makes the temperature higher. In winter, the days are shorter and the nights longer. The winter gives the sun little time to warm up the Earth so short winter days do have long, cold nights.

Speaking of winter, the shortest day is the first day of winter. For us in the north, it is around December 21st or 22nd. This day is known as the winter solstice.

Between winter and summer, we have spring. It starts on about March 20th. On this day, day and night time are each 12 hours long. This is called the vernal equinox. It is the first day of spring north of the equator and the first day of autumn in the southern half of the world.

In between summer and winter there is another equinox, called the autumnal equinox. Just like the vernal equinox, day and night each are 12 hours long. But, it is now the first day of autumn north of the equator and the start of spring to the south.

What Is In Sweat?

2003-09-15T13:36:00.000-07:00

Now that springtime has finally arrived, so has the Sun. More Sun means higher temperatures and more time to spend outside playing. Oftentimes, Sun, heat and sports equal sweat. I am sure most of you have experienced this but do any of you know why this occurs? Do any of you know what sweat exactly is? If not, read this.

Sweat or perspiration is the fluid produced by sweat glands. Sweat glands are found mainly in the skin of the armpit. But, other areas on the body produce sweat. This would include your forehead, hands and feet.

But, what is it made of? Sweat is a mixture of water, ions, urea, uric acid, amino acid, ammonia, glucose, lactic acid and ascorbic acid. What are all these things? Water is just that---water. Ions include sodium, which is represented by the chemical symbol Na+ and chloride, which is represented as Cl-. These are often thought of as together as salt. They help to make our sweat so sticky and "salty."

These important ions are taken away from the body when they are "sweated out." When an athlete exercises for several hours in the hot sun, they lose lots of sodium and chloride and other types of electrolytes. Electrolytes are any compound that separates into ions when dissolved into water and is able to conduct electricity. They are very important to helping us stay hydrated or with enough water to function. A water loss of as little as three percent hurts our ability to run, walk and think. When we sweat a lot, we lose lot of electrolytes. This is why products such as Gatorade were created. They provide athletes, who sweat a lot during workouts and games, with much needed water and electrolytes.

Okay, so we know what electrolytes are. What about all those other things in sweat? Urea, amino acid and ammonia are products that are made from the break down of protein. Protein is found in foods such as meat, fish, eggs and milk. Proteins serve many roles in the body: they help us grow, help with chemical reactions in the body, help control body processes through hormones, help protect the body against foreign invaders through antibodies, help in maintaining hydration, help maintain they body's acid-base balance, transport substances such as oxygen around the body and also provide us with energy to walk, talk and breathe. Proteins are important!

Glucose or "sugar" provides the body with energy too. Lactic acid is produced when we use up our glucose stores in the muscle. It causes the burning feeling in our muscles when we exercise a lot. Ascorbic acid or vitamin C is found in oranges. It helps with many key body functions.

All these important things are in that sticky fluid that runs down our face when we exercise outside when it is hot.

But, why do we sweat? Sweat helps to regulate the body's temperature. It provides a way to cool the body down. It also gets rid of some of the body's waste products such as lactic acid that the body does not need.

Obviously, sweating is important for the body. It is also important to remember when we are outside sweating away to drink plenty of water and, if needed, sports drinks like Gatorade to replace our lost electrolytes.

What Is The Life Cycle Of A Butterfly?

2003-08-15T13:35:00.000-07:00

Even wonder where a butterfly comes from or how it grows up? The lifecycle of a butterfly is actually not that simple. Unlike humans who look a lot alike whether they are a newborn baby or great-grandparent, butterflies go through four different life stages. In the beginning or their first stage, an adult butterfly lays an egg. Next, the egg hatches into a caterpillar or larva. You have probably seen many green or furry black and yellow caterpillars crawling around leaves, trees and your fingers in the spring and summer. The caterpillar then changes into a chrysalis (KRIS-uh-liss), which is also called a pupa. A chrysalis or pupa looks like a tiny leathery pouch. This summer look for them under leaves. When the chrysalis matures or grows up, it turns into a butterfly.

Little Lions Experiment:

Make a butterfly!

Materials:

Toilet-paper tube
Tongue depressor or ice-cream pop stick
Heavy paper
6" (150 mm) piece of pipe cleaner, folded in half
Markers or crayons
Scissors and glue

Steps:

Cut out and color a butterfly from the heavy paper. Use any colors, but make both halves look the same. Put a small hole at the top of the butterfly's head.
Color the toilet paper tube to look like a chrysalis. (A monarch butterfly's chrysalis is green, but you can use any color.)
Take a piece of pipe cleaner and shape it like the letter "V". Put one point through the little hole in the butterfly's head and then twist it to look like antennae. Butterflies use these "feelers" to learn about their environment.
Glue the butterfly to one end of the tongue depressor or ice cream pop stick. Let the glue dry.
Curl the butterfly's wings and slide it into the chrysalis.
Pull the stick to make the beautiful butterfly come out of the chrysalis.

Now that you know all the lifecycles of a butterfly and can even make one, do you want to know how to tell the difference between a butterfly and a moth? If so, this is how you do it: most butterflies hold their wings together over the back when resting. A moth generally holds its wings spread out over its body or curled up tightly around it. Another difference between butterflies and moths is that a butterfly's antennae are generally long, with knobs at the end. On the other hand, a moth's antennae lack knobs, are usually shorter, and may be fuzzy. Go outside and try to dig up, spot and find the butterfly at all four lifecycles. Make sure not to confuse a butterfly with a moth!

How Do Sounds Travel In Space?

2003-07-15T13:35:00.000-07:00

Everyone loves movies, they can make us laugh or cry or jump out of our seat! But when it comes to science, movies do not always tell the whole story.

Movies set in space are a great example. Have you ever watched a movie that is set in outer space and heard an explosion? This would never happen in space. As most of us know, space is a vacuum; this means there is a whole bunch of nothing in the air. The air here is made of tiny molecules like oxygen, nitrogen and carbon dioxide. In space, these molecules are few and far between. Sound is a wave, like in the ocean and needs molecules to be carried. So just like ocean waves need molecules of water, sound waves need molecules of air to move and be heard.

We are able to see in space because light travels in a different kind of wave called an electromagnetic wave. Electromagnetic waves do not need molecules to send their wave. Another thing related to light and sound is that they do not travel at the same speed. Sound travels at 760 miles per an hour here on earth. I would like to see Jeff Gordon beat that! In space because there are so many less molecules, it would be much slower. We are not talking slow like a turtle, but slow like going only a foot or two over millions of years. Light travels at 671,080,887 miles per an hour in a vacuum like space. We would see the explosion long before we would hear it. This is the same thing that allows us to see lightning before we hear it.

And just another point about space settings is the ever-present exploding planet or spaceship. Pieces of the planet or spaceship created from exploding objects would have an extremely high initial speed, like on earth, and then continue forever in a strait path through space. Here on earth we have gravity to slow exploding objects, in space there is little or no gravity, so the debris would travel outward in straight lines ideally forever until it impacts with something. These exploding pieces would have about the same energy or force they had at the moment of explosion, so if they impacted a ship or planet, no shield would be able to protect you!

Little Lion Experiment:

Explore physics for yourself! A common physics topic is pressure. Pressure is just the amount of force distributed over the amount of area that force is given. For instance, if you took your finger and pressed it into the arm of your sibling or parent, it would hurt quite a bit. If you used the same amount of strength and pressed into their arm with your entire hand, it would not hurt much at all. Lets try the same thing a different way!

Materials

Paper Cups
Big thin book or piece of flat, thin plywood

Steps:

Step down on a single cup. What happens?
Take the paper cups and lay them in a square a little bigger than the size of the book or plywood. Fill in the square with cups so that the cups are all right next to each other.
Place the book or wood on top of the cups.
Have your parents help you as you step on top of the book or wood. What happens? Do the cups break as they did when you stepped on just the one?

So what happened is the force (your weight) is distributed over all the cups instead of just one cup. So the cups are able to hold you up! This is the same way a bed of nails works. If you lay on one nail, OUCH! But because your weight is distributed over several nails, it is just a little prickly.

How Does A Basketball Bounce?

2003-06-15T13:34:00.000-07:00

Did you ever wonder while you were watching Michael Jordan running up the court, dibbling a basketball and shooting a game-winning final-second shot how a ball bounces?

If so, here is the answer. A basketball bounces because of air and gravity. Air makes the ball bounce because air does not want to stay up. Air wants to go down. It is like that old saying---"what goes up, must come down." This old saying is true and also describes gravity.

Scientific properties of a basketball also help to explain why if you bounce the ball hard, it will go high, But if you make a small bounce, the ball will not bounce much. This is because of elasticity. Elasticity is defined as an object's property of changing shape when the deforming force is removed. A basketball is elastic. So, when it hits a hard surface, the ball's shape is deformed and kinetic energy (energy in motion) is changed to and stored as potential energy (energy that is stored). Once the basketball returns to its original shape, potential energy is changed back into kinetic energy and makes the ball bounce. Based on this scientific principle, pulling a little muscle into your dribbling will help you make the basketball bounce higher.

Air and gravity play important roles in basketball. You have probably noticed how important air is when your ball is deflated or without air. Does a basketball without air bounce? NO! So, you need to keep your basketball filled with air. But, air only supplies a part of the energy storage in an under-inflated basketball. Another player in a basketball's energy supply is the ball's leathery skin. But, the skin does a bad job of storing the energy it gets from being bounced. It is like a leather belt. It is not very elastic. It quickly loses the energy it gets as thermal energy. These scientific properties of a ball make having a well-inflated basketball important.

Science in sports is not limited to how a basketball bounces. The following website provides more details of how science is a key player in the entire game of basketball: http: //www.physics.utoronto.ca/~rbhat/bball/physics/.

Learning more about the science of sports may help you be the Michael Jordan of your basketball team and science class.

Little Lion Experiment:

Materials:

Different types of balls (basketball, baseball, tennis balls, football, etc.)
Measuring stick
Paper and pencil
Teammate

Procedures:

Take one ball at a time and bounce it.
Have a teammate use a measuring stick to determine how high that ball bounced.
Record the type of ball you bounced and how high it bounced.
Figure out which type of ball bounced the highest. Why? (Hint: Remember air and gravity. Shape is also important.)
Pick a sport and play it often. Participating in sports is good for your heart and head.

How Do Insects Climb Walls?

2003-05-15T13:33:00.000-07:00

Everyone has seen the little critters: they fly around, climb up and down walls, and generally make themselves a big nuisance. It's the housefly, and if you look at them closely you can understand how insects can climb on a wall that no human could. Flies are just like most insects; they have six legs and three sections to their body, a head, a middle section called a thorax, and a hind section that is called the abdomen. Since flies fly, they have wings as well.

But how do they climb on walls? It helps to imagine what it would be like if we were a fly. Let's say we suddenly shrunk down to the size of a fly. Everything would be about 150 times bigger! Suddenly a piece of paper would be around the size of a 12 story building! If we walked over to a wall, we would notice that instead of a smooth surface, it actually looks bumpy and rugged. That's because everything we use, from wood to plastic, has some kind of a roughness to it. But if the roughness is small enough we don't notice it. Since we are still the size of a fly, when we go to the wall we find that it is made up of bumps and crevices about the size of a small doorknob. So if we were the size of flies, with a little effort we could climb walls too. Flies don't have hands, instead they have little hooks at the end of each of their feet. In addition, for smoother surfaces they have little sticky pads which not only help them to walk but act as tastebuds. So everytime a fly walks around, it's tasting what it's walking on! This helps the fly to find food and places to lay its eggs.

There are lots of fun facts about flies and most of them can be found either on the web or at a library near you. The one bad thing about flies (besides being annoying), is that they can carry harmful diseases. The best way to avoid having flies around is to keep everything clean and dry.

Little Lions Experiment:

Now you can see for yourself the ways a fly can walk around on walls, glass, and ceilings. Take a piece of paper and fold it into quarters. This will be your "wall." Arrange the paper so that some of the folds are peaked like mountains and others are down like valleys. This is similar to how a wall would look to a fly. Take something smooth like a ceramic tile or a coaster and place it next to the paper. Now take your pointer finger and make it into the shape of a hook. You now have a fly leg! Drag it across the paper and the tile. Next take a piece of tape and with the sticky side down drag it across the paper and the tile. Which works better on the paper? Which works better on the tile? Why do you think a fly has both?

Why Do You Get Tired After Thanksgiving Dinner?

2003-04-15T13:32:00.000-07:00

Ever feel really sleepy after Thanksgiving dinner? Ever watch your grandfather fall fast asleep after eating his Thanksgiving meal? You are not alone. Many people hit the hay after enjoying their Thanksgiving feast featuring everyone's favorite bird - the turkey. Some think that the turkey makes them tired. Is this true?

People think turkey puts them to sleep because it is made up of L-tryptophan. But what is L-tryptophan? L-tryptophan is an amino acid. An amino acid helps to build proteins. Proteins are very important to your body. Along with making up your muscles so you can move, proteins also control the billions of chemical reactions that happen in your cells every day. If these reactions did not take place, you would not be able to make stomach acid to digest your food, produce sweat to cool yourself off in the summer, get oxygen and nutrients from your blood to your cells, fight off infections or do pretty much everything your body needs to do to stay alive.

Proteins are made up of various amino acids, not just L-tryptophan. Humans need to eat nine "essential" amino acids to survive. L-tryptophan is one of these nine. It is a normal and important part of everyone's diet. L-tryptophan is also natural sedative or, in other words, a compound that relaxes people and makes them sleepy. L-tryptophan also helps to make serotonin--a normal chemical in the brain that is also a sedative. Some people actually take L-tryptophan to help them fall asleep. But, in large amounts, it is not healthy and could cause serious problems such as death. As a result, the Food and Drug Administration, the government agency that decides which foods and drugs can be legally sold in the United States, banned it from being sold in this country.

Even though L-tryptophan can help you fall asleep, it is unlikely that the amount in your Thanksgiving turkey is putting you to sleep. This is because L-tryptophan only affects the brain if your stomach is empty and there are no proteins present. Do you plan on eating only turkey for Thanksgiving? What about those delicious food items on your plate such as candy yams and cranberry sauce? And, who can forget about that pumpkin pie? Also, turkey is made up of many proteins, so L-tryptophan would not be alone in your stomach even if you did pass up all the other delicious dishes.

As you can see, if you are tired after turkey, it is probably not the L-tryptophan in your turkey that is making you fall asleep. You are probably just tired from helping your parents cook that great, big meal or from working up an appetite while playing football outside with all your cousins or from simply overeating. Overeating---not just turkey, but mashed potatoes, cranberries, yams, peas, carrots, bread, pies, and whipped cream---demands a lot of blood to be pulled towards your digestive system to help break down all that food. This blood is pulled away from your brain. Your brain constantly needs blood for you to think and be alert. Losing even small amounts can cause you to feel tired. So, if you want to stay awake for desert or to watch the end of The Sound of Music or to see your neighbors start to put up their Christmas decorations, you should probably take your time and enjoy your meal. Don't fill up! And, after that delicious dinner, take a walk or help wash the dishes.

Little Lion Experiment:

Corn was a stable food item for the Indians because it was easy to grow and very nutritious. Try to grow your own!

Materials:

Kernels of popcorn
Ziploc bag
Dirt
Water

Procedure:

Place a couple handfuls of dirt into your Ziploc bag; add a little water and a few kernels of popcorn. Then, seal the bag and place it in a sunny window. Observe your corn grow. In about a week, your corn should be sprouting

For the advanced scientist, you can make a couple bags of corn and test the effects of different amounts of sunlight, water and air. Be sure to record how much or how little you provided your kernels.

How Should You Clean Earwax?

2003-03-15T13:31:00.000-08:00

Have you ever wondered where earwax comes from? Your ear, of course! But where in your ear is earwax made? Earwax, which scientists call cerumen (pronounced suh-ROO-muhn), is made from special glands in your outer ear canal. These glands produce the gloppy substance that we call earwax. The outer ear canal is a tube between that flap of skin on each side of your head that scientists call the auricle, what most people think of as your ears, and your eardrums.

So what does earwax do, exactly? Well, your eardrum is a very sensitive membrane. It's only a few cell layers thick, so it is very important that it stays clean. Earwax protects the eardrum from dust and dirt particles that may irritate it. Dirt particles entering the ear get trapped in the gooey wax and are eventually pushed out of the ear naturally. In a healthy ear, earwax is pushed to the outside of the ear where it eventually flakes off, carrying whatever dirt and grime it has collected with it. Earwax also traps and prevents bacteria from growing in the ear canal, helping to prevent ear infections.

So how do you clean the earwax from inside your ear? You don't! Never stick anything smaller than your elbow in your ear canal! Earwax helps to prevent harmful substances like dirt and bacteria from reaching your eardrum. It also helps to keep your outer ear canal moist. Ear canals that do not have enough wax tend to become itchy. Cotton swabs should NEVER be stuck inside your ear, because they can damage the sensitive skin of your ear canal, causing it to bleed, and can even hurt your eardrum. Sometimes, using things such as cotton swabs or pencils will push earwax back into the ear canal and up against the eardrum. This is BAD! If this happens, it may be difficult to hear very well. Although there are some over-the-counter remedies for compacted earwax, should this happen to you, you should have your parents call your doctor and ask what the best treatment is. A healthy ear canal will naturally push out old wax, keeping itself clean.

So how do you clean the earwax from outside your ear? All you really need to do is wash your hair to clean your ears. The soap and lather from washing your hair will get into the folds of the auricle, the part of the ear you can see, and help wash away old, flaky earwax. You can also put a cloth over your finger, and wipe the folds of the auricle, but do NOT stick your finger into the ear canal.

Little Lions Experiment:

Materials:

2 old paper towel tubes (outer ear canal)
2 sheets of facial tissue (eardrum)
petroleum jelly (earwax)
dust, dirt or lint (grime)

Steps

Tape a sheet of facial tissue to one end of the paper towel tubes. Make sure one end of each tube is completely covered by one layer of tissue.
Spread petroleum jelly inside one of the tubes. Leave the other tube without any petroleum jelly. Only spread the jelly in the upper half. Do not let it go too far down the tube. Do not let it touch the facial tissue.
Set the tubes beside each other, and prop up the open ends about 30 degrees.
Throw the dust towards the tubes.
Carefully remove the tissue paper. Compare how dirty the tissue paper got for the tube with the jelly and without the jelly. Did the earwax prevent the grime from hitting the eardrum?

Why Don't Animals Need Glasses?

2003-02-15T13:30:00.000-08:00

Roughly, forty percent of people wear contacts or glasses. Some scientists think that the cause is genetic and some think is because of our surroundings.

Scientists have been able to show that people who look out over long distances, like sailors, often do not have problems with short-sightedness or are not myopic (MY-OP-ICK). People such as tailors who have to focus their eyes close to their face often are myopic. It seems that muscles on the side of the eye will correct the eye and help it to see more clearly. If you were to travel to primitive parts of the world, you would see people who have excellent vision without the help of glasses.

Monkeys that have been taken from the wild and held in captivity have been shown to only focus on this close to them. They have become unable to focus far away. Scientists gave chickens glasses and showed that they could cause the chickens to be nearsighted (see things only close to their face, or beaks) for a short time. Imagine a chicken with glasses!

Another theory as to why animals are able to see well is because those that cannot do not live for very long. This is the survival of the fittest theory. That animals that are the strongest will survive the longest and make more animals that are the strongest.

Among domesticated animals, or animals taken from the wild, like cats and dogs, eye problems are likely as the animal gets older. Older domestic animals and humans typically get what are called cataracts (CAT-TER-ACTS). Cataracts are when the front part of the eye becomes cloudy and hard to see through. Have you ever seen an old dog with blue-grey hazy eyes? This is probably because of cataracts.

Little Lion Experiment:

Do you or people in your family wear glasses? Try on some of your family members' glasses and see if you can figure out if they are near- or far-sighted. Do not keep the glasses on too long; they might give you a headache!

Do you see a pattern in the age of the person wearing the glasses and the strength of the glasses? Do older people in the house have stronger glasses than younger people?

A good scientist always looks for trends in the results from their experiments.

Perform a search on the Web for information about the eye and vision problems. Pages like http://www.google.com or http://www.yahoo.com are good search engines. If you just search on eyes, you will get a lot of information.

How Does A Pencil Eraser Work?

2003-01-15T13:29:00.000-08:00

When the pencil is used on a sheet of paper, the graphite particles lie slightly below the surface of the paper, interlocked between its fibers. A single rub using an eraser sufficiently soft to reach between the fibers will pick up most of them. Looking at the eraser you can see undamaged graphite piece sticking to the surface. An effective erasing material scratches the paper surface, producing the familiar small spindles of rubber or eraser material, which wrap up the graphite particles. When you look at these under an optical microscope at 200 times magnification (200x), these look like roly-poly puddings studded with graphite raisins.

Little Lion Experiment:

Erasers come in a variety of colors: white, pink and gray are some of them. Sometimes the color difference is because of a dye or because the eraser is made of a different type of rubber. Go around you house and see how many types of different erasers and pencil leads you have; number two and number three pencils are different types of leads. Remember the bright-colored erasers, like purple and yellow, are usually white erasers in disguise! If someone in your home has a mechanical pencil, you can purchase different types of lead, like HB or soft, they might have different leads you can use. You can also use erasable pen as a lead type. See which one of these works best with different types of pencils and ink. Can you erase the ink with a pink or white eraser? Is there one eraser that works for all lead types? Knowing what you know about how erasers work, why do you think certain erasers do not work with other types of pencil lead and ink?

Thinking about experiments, scientists look at the different things or factors in the experiment called variables. The variables you have in this experiment are erasers and lead types, assuming you always use the same type of paper. A scientist is always concerned about the number of variables in there experiments because it tells them how many experimental runs they need to do. An experiment run would be a single type of eraser against a single type of lead. The total number of experimental runs you would do in your experiment are the number of erasers times the number of leads. By limiting your variables you limit your number of experimental runs, but you don't want to limit your variables too much otherwise your experiment will not be conclusive or lead to a correct answer that may be misleading. For example, if you use all the lead and eraser types in your house, you can say that you have a conclusive study of the erasers and leads in your house. If you just look at the erasers and leads in your room, you could not say that you know about all the erasers and leads in your house, just about the ones in your room. Sometimes scientists limit there variables, like for instances just the erasers in just your bedroom, and then predict from those experiments to say how the erasers in the house would perform. Not all predictions are good, but sometimes it is the best a scientist can do.

How Do Chicken And Turkey Have Dark And White Meat?

2002-12-15T13:28:00.000-08:00

Ever wonder why turkey legs at Thanksgiving have dark meat, while the breast meat is white? The simple answer is because dark meat has more blood vessels giving food and oxygen to those areas than white meat does. But there is much more to the story. Both white and dark meat are skeletal muscles--the kind of muscles that help you move. Muscles contract or shorten, and relax or get longer in order to help you move. The meats are different kinds of skeletal muscles, leading to their different colors. There are three main groups of skeletal muscles: fast twitch glycolytic (GLY-CO-LIT-IC), fast twitch oxidative (OX-A-DATE-IVE) and slow twitch.

What do these words really mean? Well, the muscle groups are named for how they work. The fast twitch glycolytic muscles are powerful muscles that contract or work quickly, but they tire out quickly too. Sprinters who run short distances have trained their legs to use many of these quick working muscles. Muscles that tire out quickly would not be much use to marathon runners who need lots of energy for longperiods of time. Marathon runners have more of the fast twitch oxidative muscles. These muscles also contract or work quickly, but tire out slowly. The reason they do not tire out as quickly as the fast twitch glycolytic muscles is that they have large numbers of factories producing energy especially for them. These energy factories are called mitochondria (MI-TO-CON-DRI-A) and they make energy for cells.

So we have muscles that contract quickly, but tire quickly and muscles that do not tire quickly but use up a lot of energy. What do we do when we need a muscle to contract or work all the time without using up all of our energy? We do not want to be walking around as if we just ran a marathon all the time! Imagine how tired we would be! This is why we have the slow twitch muscles. The slow twitch muscles are like the ones in our back. They are always contracted so we can sit up straight in our chairs. These muscles contain lots of blood vessels so that they can always get food and do not have to produce lots of their own energy with the help of mitochondria. Our body needs all three types of muscles to work properly.

But what does this have to do with chicken and turkey? What type of muscles do you think make up light and dark meat? Let's think about here the dark meat is on a bird. It is found in the thighs and drumsticks. Chickens and turkeys are always on their feet and they do not need to move quickly. Dark meat is therefore a slow twitch muscle. What about white meat? Birds fly rather then walk to get away from something. So it would make sense that they would have fast twitch muscles to help them fly. That is why you find white meat in the breast of a bird. Although chickens cannot fly like turkeys can, they are relatives of birds that can fly and that is why they still have white meat or fast twitch muscle that move their wings.

Little Lion Experiment:

Can you identify where all the different types of muscles in your body are found? Run a sprint down your block and see which muscles you use. Run a around your block a couple of times and try to figure out which muscles you use. Those are your fast twitch muscles. Think about what muscles would be your slow twitch muscles.

Next time your mom or dad has a whole chicken or turkey for dinner ask them if you can identify the different types of muscles while they cut it up. Let your parents handle the knife to cut up the poultry and always wash your hands after handling raw poultry.

What is a Nerve?

2002-07-15T13:28:00.000-07:00

A nerve is a cell that is specialized for sending and receiving information. Nerves make up the part of your body that tells your brain what your body is doing, called the peripheral nervous system. Your muscles, your stomach, and even your heart would not function if a nerve didn't send it directions from your brain.

Nerves carry signals like wires carry electricity. The long nerves in your body are like wires and the current would be the signals carried in the nerved. Charged atoms called ions carry nerve signals. The ions move in an out of the nerve cells in a wave-like manner down the nerve. This causes a charge to move down the nerve, this is how a nerve signal is carried. The longest nerve is the body is called the sciatic (si-at-tik) nerve and it is in your leg.

The sciatic nerve is a single cell that begins in your lower back by your spine and runs to the heel of your foot! Some nerves only send instructions from your brain to body parts; other nerves are there to report back to the brain on what is happening to your body. A nerve can actually sense changes in temperature, pressure, pain, or light, if the nerve has the right molecules. That's one exciting area of neuroscience (the study of brain stuff): neuroscientists are trying to figure out what types of molecules are found in each different nerve in your body. If you know what molecules are there, then you have a pretty good idea of what each nerve does.

When nerves are in your brain or spinal cord, we call them neurons instead. These neurons are part of the central nervous system. Neurons are a bit more complicated because instead of just sending information from one place to another, like a nerve, each neuron makes thousands of connections to other neurons. This means that the information can be sent backwards, forwards, sideways, even back in circles inside your head. We think that thinking has a lot to do with the complex pattern of information flowing in your brain. And when you think that these patterns in your brain are a million times more complex than the circuitry of the fastest supercomputer, your brain might just fry trying to comprehend its own complexity.

Consider this. Look up at the sky tonight. Try to count all the stars you can see without counting the same one twice. Now, imagine that each of these stars has nine planets like our solar system, and that each planet has nine moons orbiting it. Now imagine if you could draw lines connecting every moon on every planet to every other moon, creating some sort of a web across the sky. This "web" would look a little like the connections between all the neurons inside your brain.

However, your brain is even more complex than that! Your brain actually contains 10,000,000,000 connections between all the neurons, which is a network so complex, you would have to connect all the stars in the galaxy, including all those you can't see when you look up at the sky, to paint a picture like the complex web inside your head.

Why Are The Basic Colors Different In Paint And Televisions?

2002-06-15T13:27:00.000-07:00

The reason why this phenomenon occurs is because rules in mixing paints, inks, and dyes are not the same as those in mixing light. When a painter looks at their palette they can create any color with the three primary pigments: magenta, cyan, and yellow. It is not the same for a projection television. Colors such red, blue and green (called primary colors) are used to create all of the colors.

When the three primary colors of light are mixed, the intensities of the colored light are added. An example of this is where primary color light overlaps. When red light is added to green light, yellow light is formed. All colors can be made by the addition of different lights of the three primary colors. For example, red is 100% of red light and red light only. Blended colors like orange are 1 part green and 2 parts red light. Some color mixing is very complicated, like for instances gray is 3 parts red, 3 parts green and 1 part blue. The equal mixture of all three primary colors forms white light.

Our eyes are like television, in that they mix the primary colors of light to form an image. The human eye consists of two types of light receptors, rods and cones. Rods are used for light at low levels, like when you are in the dark. Rods in your eyes tell your brain to see things in black and white, so they perceive how much dim or intense the image is. Cones are what we use to see color. There are three types of cones: cones sensitive to red, blue and green. Based on how much each type of cone is stimulated due to the specific light, we perceive the color of light. For example if both red and green cones are stimulated, then we perceive yellow light. If only green cones are stimulated, we perceive it as green light. These three types of cones generate color vision.

Whereas primary colors are mixed in an additive manner, primary pigments are mixed in a subtractive manner. The primary pigments for mixing dyes used in coloring, photography, and printing are: magenta (light purplish pink), cyan (light blue) and yellow. The dyes of inks absorb certain colors. Any color that is not absorbed (subtracted) is the hue that we see. These dyes act as filters that subtract one or more colors. By varying the proportion of the colors in a mixture, a full range of colors can be produced. For example, the color yellow absorbs blue and reflects red and green. Magenta absorbs green and reflects red and blue. So, the mixture of yellow and magenta equals red (white minus blue minus green equals red). The mixture of all primary pigments is black, all light being absorbed.

In printing, the primary pigments are layered. A white layer is laid down first, followed by a yellow, magenta and cyan layer. Each pigment layer is carefully laid out to create a final image with the desired colors

What is Octane?

2002-05-15T13:26:00.000-07:00

Most have heard the word octane used in regards to the hydrocarbon fuel gasoline. Octane is actually the generic name for molecules having eight carbon atoms and the chemical formula C8H18. More commonly, octane is used in reference to grades of gasoline. In this case, the numbers seen at the pump, 87, 89, and 93, refer to the fuel's octane number. So what vehicle owners are actually interested in knowing is "What is octane number?" Before getting into what octane number is and what it means to gasoline consumers, it is useful to have a basic understanding of how an engine works.

Vehicles that use gasoline have a four-stroke spark ignition engine. The first stroke is the induction stroke. The piston travels down the cylinder. A valve is opened allowing a mixture of fuel and air to enter into the cylinder. Next is the compression stroke. In this stage of the cycle, the valves are closed, and the piston travels back up the cylinder causing the air and fuel mixture to compress. When the piston has traveled to the top of the cylinder, the spark plug fires, causing the air-fuel mixture to ignite. The flame propagates through the mixture causing the temperature and pressure inside the cylinder to increase. The mixture expands forcing the piston down in the power stroke. Finally, the exhaust valve is opened and the piston travels back up the cylinder expelling any remaining gases in the exhaust stroke.

Under the high temperature and pressure conditions of the compression stroke, it is possible for the fuel-air mixture to ignite without the spark plug. This phenomenon is known as engine knock. Engine knocking is bad for a vehicle. It reduces a car's gas mileage and acceleration, creates wear and tear on parts, and in severe cases can lead to engine failure. Octane number is a rating that refers to a fuel's resistance to auto-ignition under specific engine conditions. Specifically, the octane number is the percentage of "octane" (2,2,4-trimethylpentane) blended with another chemical called pentane, that is required to achieve the same knocking characteristics as the fuel being tested. Since octane is very resistant to knocking and pentane knocks very easily, the higher the fuel's octane number the less likely it will cause engine knocking.

So why are there three different octane numbers? The different grades of gasoline are needed to match the different types of engines available. The most important engine characteristic to consider is the compression ratio: the ratio of the volume of the cylinder at the piston's lowest point and the volume at the piston's highest point. A car with a high compression ratio will perform better in terms of acceleration and power but will also subject the fuel to more severe temperature and pressure conditions, and will therefore require gasoline with a higher octane number. For example a Porsche 911 has a compression ratio of 11.3:1 and requires 93 octane number gasoline, while a Mercury Tracer has a ratio of 8:1 and requires 87. Consult your vehicle's owner's manual to determine the best grade of gasoline for your vehicle. You may be spending extra money on premium gasoline when you don't really need to.

Why Does Ice Float?

2002-04-15T13:25:00.000-07:00

Now that winter has finally arrived here in Happy Valley and the ice outside is enough to keep even you in bed, have you ever wondered why it is that ice floats on top of water? Why is it that your solid ice cubes float to the top of your glass of water? Nearly every solid, if placed in its liquid form, will sink to the bottom. Luckily for us, the properties of water are different.

The meaning behind this mystery lies in the different properties of solid and liquid water. Unlike most other substances on Earth, the solid form of water floats on the liquid form. This is caused by the change in density, the amount of mass in a volume. With the exception of water, most substances on Earth become denser as they become colder. The solid ice will float because its density is lower than that of water. It is about 9% less dense than water. The denser water sinks to the bottom forcing the less dense ice to the surface.

What makes water molecules different from other molecules is that they attract each other in an organized fashion. As the water cools, the molecules begin to bind to each other, forming a hexagonal pattern. Water is at its densest point at 4C. After that point, the water molecules move very slowly and attract to each other. In most substances, the molecules are more tightly packed together in solid form. But in ice, the hexagonal pattern of the attracting water molecules leaves empty spaces. This is why your water expands when making ice cubes. The empty space between the hexagonal shapes makes the solid form less dense than the liquid form so that it floats to the top.

Thanks to this oddity of physics, the water in our oceans and seas remain in liquid state. If the solid form of ice happened to be denser than water, the ice would sink to the bottom. If this happened, the ice on the bottom would begin to freeze up toward the surface. Eventually, nearly all the water on Earth would become solid ice and never melt. Luckily, ice floats and remains on the surface so that the water underneath remains in liquid form.

This trait of physics also applies to other forms of water. "Heavy water" is used to cool nuclear reactors. An ice cube of heavy water will sink in ordinary water. Ordinary water contains two hydrogen atoms, but heavy water has two deuterium atoms. This causes a difference in weight. Deuterium atoms weigh about twice as much as hydrogen atoms and the extra mass of the deuterium adds enough weight so that an ice cube of heavy water sinks in ordinary water. But like ordinary water, an ice cube of heavy water will float to the top of a glass of heavy water.

So on your next icy Monday morning or tall glass of ice water, remember that density causes solid ice to float on liquid water.

Why Do I Get A Headache When I Eat Ice Cream?

2002-03-15T13:24:00.000-08:00

I scream, you scream, we all scream for ice cream. Ouch! Some of us scream more than others. The University Creamery is a summertime hot spot , but for some people eating ice cream can be a painful experience. The ice cream headache or brain freeze as it is some times called occurs in about one in three people when they eat cold foods like ice cream or popsicles. The headache typically lasts from 15-30 seconds, but for some unlucky people the suffering can last up to five minutes.

You can't blame your mint chocolate chip because it's not the ice creams fault. Located on the roof of the mouth, near the back, there is a nerve center. Its job in part is to control the temperature of your brain. Like the thermostat in your house, this nerve center senses the temperature and can turn the heaters on or off. When the Peachy Paterno contacts the roof of your mouth, it cools down the nerve center making it think that your brain is dangerously cold.

The nerve center's thermostat reacts by turning the heaters on full blast. Blood vessels (tiny tubes that carry blood all over your body) in your head dilate or swell with extra warm blood that was meant to heat your brain. The extra pressure on your blood vessels causes the painful headache. Even though we call it brain freeze, the brain really isn't involved at all. The medical term for an ice cream headache is spheno palatine ganglioneuralgia. The condition is caused by a constriction in the blood vessels supplying the brain that lie just above the palate area.

The simplest way to avoid a brain freeze is to not put anything cold against the roof of your mouth. Let the food warm up a little in the front of your mouth before swallowing it down.

If you still end up with an ice cream headache there are several solutions you can try. The most common solution is to warm up your nerve center again. Pushing your tongue or your thumb against the roof of your mouth (and towards the back) will reheat the nerve center and turn off the headache. Other cures include: placing an ice cube against your inner wrist, eating a pinch of salt, and bending over to put your head below your heart.

Now you know how to beat that butterscotch, but you'll probably have to wait for summer to try it out. That's because most people don't get ice cream headaches unless the weather is warm. Good luck.

What is Malaria?

2002-02-15T13:23:00.000-08:00

Malaria is an infectious disease characterized by fever, chills, nauseau, and general discomfort. It is caused by a single-celled parasite known as Plasmodium that infects and destroys red blood cells. Malaria is transmitted or passed by a mosquito that bites an infected individual, carrying the parasite to another person. More than 24 million people are infected with Plasmodium each year and 3 million people, mostly children, die from the disease.

Malaria has been around since the times of Ancient Egyptians. It used to be very widespread, effecting all of Africa, Asia, South America, southern Europe, and even North America. Cases as far north as Philadelphia used to be common occurrences. Today, the areas affected by malaria are somewhat smaller, mainly due to changes in the water systems in the early 1990s. Sub-Suharan Africa, Central America, and Southeast Asia are still hard hit areas.

There are three main ways to combat malaria. The first is to get rid of the mosquito population that transmits the parasite. This can be done by removing free-standing water that has accumulated in jars, tires, and other containers. Sewers can also be built to drain areas that have a lot of free-standing water. Spraying houses with insecticides, which are chemicals that kill insects without harming the environment or humans, can also terminate mosquitoes. A common spray that was widely used was DDT, although its use has recently been banned. The second way to combat malaria is to reduce the amount of exposure that humans have to mosquitoes. This includes wearing long sleeved shirts and pants when outside, sleeping under bed netting, using insect repellent, and staying indoors at dawn and dusk--the two times of the day when mosquitoes are the most active. Finally, if someone comes down with malaria there is a wide range of drugs that can be used to treat that individual. The most commonly used drug is chloroquine.

Unfortunately, many people who are administered chloroquine do not finish their recommended treatment. This, coupled with dramatic, but insufficient, worldwide efforts in the 1950s to spray areas with constant or endemic malaria, have resulted in the emergence of drug-resistant parasites and pesticide-resistant mosquitoes. This emergence has serious consequences for world health. Areas that are now malaria-free may experience a reoccurence of the disease. Luckily, researchers around the globe are focusing on finding new treatments for eradicating malaria.

What is Arteriosclerosis?

2002-01-15T13:22:00.000-08:00

Arteriosclerosis is such a big word, but if we break down the word, maybe we can understand what it means. Arterio is what doctors call anything that deals with arteries, or the blood vessels that carry blood away from the heart; doctors use the word sclerosis when talking about something hardening. So when a doctor says the word arteriosclerosis, they mean hardening of the arteries. An artery affected with arteriosclerosis has fatty streaks, which are white or yellow lines down the middle of the artery. By age 25 most Americans have a fatty streak present in one or more of their major arteries. Fatty streaks are typically larger and more numerous in individuals with high cholesterol diets. Anything high in animal fat is considered to be high in cholesterol.

Cholesterol needs to be carried in the blood so that cells throughout the body can get the cholesterol for their membranes and steroid production (a cell's surface is called a membrane.). Cholesterol mixes with blood like oil mixes with water. In order for it to be carried in blood, it must be carried by a lipoprotein, which is a combination of a lipid (like fat) and a protein. The lipoprotein can carry cholesterol because one side of the molecule likes blood and the other likes cholesterol so a bunch of these lipoproteins surround the cholesterol while it is carried in the blood. The process of getting the cholesterol-carrying lipoprotein to the cells goes wrong with arteriosclerosis.

To understand how arteriosclerosis affects an artery we must first look at what makes up an artery. Going from where the blood is in the artery and moving out, arteries are composed of special skin cells, muscle cells, and connective tissue with skin cells. The skin cells in your arteries are not the same as the skin cells on your arm, but they do protect and form a barrier just like the skin on your arm. The skin cells inside your blood vessels, scientifically known as endothelial cells, serve as a sort of filter between the blood and the cells. Part of the way they filter the blood is by taking in only specific components of the blood.

One of these components is the cholesterol-carrying lipoprotein called low-density lipoprotein, or LDL for short. The endothelial cell pushes the cholesterol out of the other side of the cell, away from the blood side. Cholesterol then gets 'stuck' in between the skin and muscle layer. Neighboring cells and other cholesterol-carrying LDL molecules join the stuck cholesterol and the fatty streak grows. In addition to other cells and cholesterol-carrying LDL molecules, calcium can deposit in the fatty streaks. The presence of calcium causes the arteries to become hard and rigid. Typically our arteries are elastic and can stretch to help keep our blood pressure constant. When arteries become hard and cannot stretch, our blood pressure can increase. This is one of the reasons why doctors, nurses, and physician assistants keep track of our blood pressure so they can tell when it has gone up.

As the fatty streak grows and the artery becomes more and more rigid, the opening for the blood to move through become smaller and smaller. Sometimes total blockage can occur arteries. The fatty streaks can also burst when they become large and broken off parts can block small arteries. When arteries are blocked, a stroke or heart attack can occur. This is why arteriosclerosis is a major health concern in America. The arteries most prone to fatty streaks are the ones that supply blood to the heart (coronary arteries) and to the head.

For more information on arteriosclerosis, visit the Vascular Disease Foundation's website at http://www.vdf.org .

What Is The Leonid Meteor Shower?

2001-12-15T13:21:00.000-08:00

The week before Thanksgiving, many people enjoyed the Leonid meteor shower, which was one of the heavier showers in recent times. Even more amazing is the journey each meteor takes from its formation to its fiery end.

Meteors are typically small dust particles that originally were part of objects called comets. Comets are icy remnants of when our solar system was forming, large hunks of ice, rock, and dust. Comets occasionally will enter the inner part of the solar system and the heat of the Sun will start to evaporate the ices. The dust contained in the ice that evaporates will be ejected. This dust is called a meteoroid and will range in size from a few microns to several millimeters or larger. Some of the dust will collide with the Earth, typically at speeds on the order of 10 km/s (roughly 22,000 mph) and at a height of roughly 100 km or 62 miles. Larger particles (about a millimeter) will vaporize from the collision and create light, the familiar "shooting star" that people see. This is a meteor. If a particle survives its fiery entry into the Earth's atmosphere and lands, it is then called a meteorite.

What is special about the Leonids (and the Perseids in the summer) is that these are periodic showers that correspond to specific comets. The orbit of the Earth intersects the orbit of two comets, named Comet Swift-Tuttle and Comet Temple-Tuttle. Temple-Tuttle is responsible for the Leonids. The peak of the Leonids always occurs a few years after the comet passes by Earth on its journey around the sun, which is approximately every 33 years. After the peak, the Leonids aren't so spectacular. The reason for this is a large cloud of dust from Tempel-Tuttle follows a little bit behind the comet. When the Earth plows into this dust cloud, a meteor shower is born. The Leonids get their name because the meteors seem to radiate away from the constellation Leo. The Perseids seem to stream away from the constellation Perseus.

Meteors are very fun to go out and watch, but you need to find a dark place, dress warmly (even in summer), find a comfortable place and look up! Meteors can happen all over the sky so the best thing to do is lay back and try and look at as big a chunk of sky as possible. Then you relax and take in the beautiful sight of a teeny piece of dust that has spent billions of years locked up in ice, been thrown into space, and vaporized just for your enjoyment.

What is Cloning?

2001-11-15T13:20:00.000-08:00

The word "cloning" generally conjures up images of armies of identical people, grown in huge test tubes, marching onward to some evil purpose. In reality, however, cloning is not nearly so sinister. Cloning simply refers to making identical copies of something from one unit. Usually when scientists talk about cloning, they refer to DNA, bacteria, or cells. Cloning bacteria is simple. It is done by separating bacteria out so that only one bacterium is present. This bacterium will divide and form a colony of millions, all of which are identical to the first one. Since they are identical, they are clones. DNA is cloned a little bit differently. Cloning DNA means making an exact copy of some part of the DNA that is of interest. This could be a gene, for example. That copy is then amplified into many copies. Since each one is identical, they are called cDNA, short for cloned DNA.

It is also possible to clone organisms bigger than bacteria. Plants are sometimes easy to clone. Certain types of plant cells, if treated properly, will grow into entire new plants, identical to the original plant on a genetic level. Animals are harder to clone, but it is very possible to clone them. Animals can be naturally cloned in the case of twins. With identical twins, the fertilized egg separates and grows to make two embryos instead of just one. This makes them clones, since they are genetically identical. Scientists have been able to duplicate this process in animals for a long time. A more important method of cloning is called somatic cell cloning. In this method, DNA from an adult animal is used to make a new organism. Basically an identical twin is created from an adult. This is much more difficult to do, because as animals grow and develop different organs and tissues, the DNA in those tissues is modified. Some DNA is locked up, unable to be used in different parts of the body. In order to make a complete cloned animal, however, all of the DNA must be accessible. Scientists conquered this challenge, and the first somatically cloned sheep was made in Scotland in the year 1997. Her name is Dolly.

Dolly was made by taking the DNA from her mother and putting it into a sheep egg cell that had had the DNA removed. This cell was then implanted in a normal sheep uterus and grew just like a normal embryo. Therefore, even though Dolly is a clone of her mother, she is several years younger. This is important to understand. Clones are not grown in tanks by scientists in labs. They do not emerge fully grown. There has been much discussion about human cloning recently. Because it is possible to clone sheep and other mammals, it should be possible to clone a human being. However, there are very serious ethical considerations to consider. It may be possible to clone yourself, and therefore have a supply of perfectly matched organs for transplantation. However, it is probably not ethical to create people just to harvest their organs. It may also be possible for such things to happen as a woman to give birth to her twin sister. Because of these unresolved issues and dangers, it is currently not legal for anyone in the United States to clone a human being using government money.

What Makes Stainless Steel Stainless?

2001-10-15T13:20:00.000-07:00

The surface of most steel dulls and rusts when it is exposed to air and moisture. This chemical reaction with the environment (called corrosion) returns the metal to its mineral state; the steel is transforming back into iron ore. This process is prevented in stainless steels, which retain their metallic luster or shininess. By definition, stainless steels contain at least 10.5% chromium and often contain other elements like molybdenum and nickel. In stainless steels the chromium atoms at the surface react with air and moisture to form a tough, thin layer of protection. Just as a raincoat keeps you from getting wet in a rainstorm, the protective layer insulates the steel from the environment. This layer prevents the chemical reaction that produces rust.

Stainless steel is not a single material, but rather a broad category made up of dozens of different steels. Each stainless steel is unique, varying by the structure of the metal and the amount of alloying elements added to it, but they all increase resistance to rusting and other forms of corrosion. Some stainless steels are very hard and strong, but provide less protection from corrosion. Others are really good protectors, but are softer and weaker materials. A few stainless steels are both strong and very resistant to corrosion, however these are so expensive and are used only when it is absolutely necessary.

Little Lion Experiment:

Here is a simple experiment you can try in your own kitchen (with a parent's supervision). Many kitchens have a stainless steel sink and almost all have stainless steel cutting knives. However these two stainless steels are very different. To illustrate this you can test the stainless steels with a magnet; a refrigerator magnet will do nicely. Try sticking the magnet to the side of knife and to the side of the sink. What happens?

The magnet sticks to knife, but it won't stick to sink. This is because they are made from two very different types of stainless steel. A materials engineer selects the stainless steel with the best combination of strength, protection and affordability for each application. The knife must be hard to stay sharp and still not rust; it is made of ferritic stainless steel. The sink must have good protection because it often gets wet and it must be soft for shaping; it is made of austenitic stainless steel. The magnet is a simple way to tell these two types apart.

What is the Aurora?

2001-09-15T13:18:00.000-07:00

Just in the last week or so, people have been talking about the aurora, because it was visible in our night skies not too long ago. If we're lucky, we will see it again. But what is it? The aurora borealis is a beautiful display of lights that can be seen over the northern pole of the Earth. It will appear in the northern part of the sky and have a ribbon-like shape that changes and shimmers in time. It will have hues that range from very pale white to green to blue and sometimes purple. Usually it is most visible in more northern latitudes, such as Canada and Alaska, although if it is bright enough and large enough it can be visible as far south as Florida.

There is a similar phenomenon called the aurora australis in the southern hemisphere that behaves the same way. And this gives us the first clues as to where this beautiful display of lights comes from. The north and south poles of the Earth correspond roughly to the poles of the earth's magnetic field. And just as iron filings are attracted to the north and south poles of a bar magnet, the Earth attracts charged particles such as protons to its poles. These particles originate from the sun, which gives off a slow stream of these particles in what is called the solar wind.

If these charged particles strike the atmosphere, they will inevitably crash into an air molecule or atom and often the collision will eject an electron. Since air molecules and atoms like to keep their electrons they will eventually snag a new electron. That process releases light and voila you have an aurora. Because the aurora depends on the solar wind, as the solar wind changes so does the aurora. If there are lots of particles streaming from the sun, then there will be a bright aurora. This year we are lucky, the sun is very active and so will often eject lots of material into space which causes very strong and beautiful auroras.

The last time I saw the aurora was here in State College while watching for meteors. A few days before, the sun had a huge flare which released a very strong solar wind, creating a beautiful addition to the already fun hunt for meteors! If you want to try to see the aurora, the best place to be is somewhere dark and relatively flat so that you can have a good view of the horizon. You need to look towards the North.

The best way to do that is to find the Big Dipper, which looks like a huge ice cream scooper. The two stars at the edge of the scooper form a line that will point you towards the pole star or Polaris, which is due north. You also need to go out on a night when they predict that the aurora will be strong, since we don't often have a good chance of seeing it. Websites like space.com, spaceweather.com and skyandtelescope.com will have stories with links to forecasting sites and email alerts so you can try and find the likely days of next big storm.

What is Thermodynamics?

2001-08-15T13:18:00.000-07:00

The history of thermodynamics dates back to the nineteenth century. The field was developed to describe the operation of the steam engine, hence the title thermo (heat) - dynamics (power). In present day, the study of thermodynamics includes so much more than just the study of steam power. It is used to understand all sorts of thing including reactions in the cells in your body and mixtures of different liquids and gases.

Thermodynamics is based on three main laws. Like many scientific laws, these laws cannot be proven through math, but have not been proven wrong in nature. These laws are the same laws that scientists and engineers discovered when they were looking at steam and steam engines. They learned that the laws that steam obey in the engine works for all sorts of systems and chemicals.

The first law of thermodynamics states that the amount of energy in the universe does not change. When energy disappears in one form, it appears as another at that same moment. To understand this better we will look at the two main types of energy, kinetic and potential. Kinetic is the energy of motion and potential is stored energy. A car at the top of a big hill is full of potential energy, because of the difference in height at the top and bottom of the hill. As the car goes down the hill, potential energy is released in the form of kinetic energy. Potential energy can also be stored in chemical bonds. Bonds are what keep molecules together, like hydrogen and oxygen in water. When a molecule is made from atoms, energy is used to create the bonds. A good example of chemical bonds releasing energy is a campfire. The chemical bonds in the wood break producing heat and light. Sometimes a campfire crackles; this is another way energy is expressed, sound. Energy can be released from bonds as heat, light and sound.

The second law of thermodynamics says that the amount of energy a system puts out can not be greater than the amount of energy put into the system, or simply, you can not get something for free. This rule also tells us that nothing is perfect. We can look at a car engine as an example. All of the energy stored in the chemical bonds of the gas is not converted completely to energy to drive your car. The law tells us that the energy in a system cannot be made totally into work, that no engine is perfect. This is why a perpetual motion machine cannot be made. A perpetual motion machine is an ideal, fantasy machine that the operator can start moving and run forever without adding any energy once it has started. Here is a web page that discusses the history of the perpetual motion machine: http://www.phact.org/e/dennis4.html.

The third law of thermodynamics states that all things will become less and less organized. Scientists and engineers have a term called entropy. Entropy helps relate how chaotic or disorganized a system is. At the coldest temperature, absolute zero (-270 degrees Celsius), the absolute value of entropy is zero. An example of why this law is thought to be true is the constant expansion of the universe. The entropy at the time I wrote this article is less then the entropy when you read this article!

The laws of thermodynamics are universal for everything and have yet to be proven wrong!

Why is the Sky Blue?

2001-07-15T13:17:00.000-07:00

Light travels in waves, similar to waves on the ocean. The science term for light waves is electromagnetic waves. Like waves on the ocean, electromagnetic waves can be measured by their wavelength. This is the length between two crests in the wave. A crest is the top part of the wave (the foamy white part). Light coming from the sun is made up of all the colors of the rainbow and is known as white light. All the colors in white light have different wavelengths. Red light has the longest wavelength of all the colors. This wavelength is larger than the oxygen atoms in the atmosphere. When red light passes through the atmosphere, its long wavelength causes it to pass through the oxygen atoms without being scattered or spread around. Blue light on the other hand has a much shorter wavelength than red light. The wavelength of blue light is smaller than the oxygen atoms and when blue lights passes through the atmosphere it collides with the oxygen atoms. These collisions cause the blue light to be scattered in all directions. This scattering of the blue light is what causes the sky to appear blue. All other colors, with longer wavelengths than blue, are scattered as well, but blue light's short wavelength causes it to be scattered the most. Actually violet light has the shortest wavelength of all the colors and is scattered even more than blue light, but our eyes our much more sensitive to blue light so we see the sky as blue.

During a sunset, the white light has to travel through much more atmosphere than when the sun is directly overhead. The blue light and other short wavelength colors are scattered around and diluted so much by this that only the longer wavelengths of light remain. This is why the sky appears red, orange, and yellow during sunsets.

Information to answer this question was found at http://www.why-is-the-sky-blue.org/

What Is A Virus And Why Are Viruses Worse Than Bacteria?

2001-06-15T13:16:00.000-07:00

There are many different types of viruses. Some viruses cause diseases, and some do not. Viruses are all very small, and they are all made out of proteins and genes. Some viruses also have a membrane, like cells do. There is a debate about whether viruses are alive or not. They may be alive because they are able to copy themselves, and they are made of protein and nucleic acids, like all other life is; however, viruses cannot do anything by themselves. Because they are completely dependent on a host for everything, some people do not consider them to be alive.

In order to copy themselves, viruses must enter a cell. Once they are inside, they take over the machinery in the cell and use it to copy their DNA or RNA and to make virus proteins instead of the normal proteins a cell would make. Different kinds of viruses can grow in just about any kind of life. There are viruses that infect animals, plants, and even bacteria. Since viruses are so good at taking over cells, they make loads of virus copies that then go on to infect other cells. There are some viruses that make so many copies that there are a trillion (1,000,000,000) viruses in one milliliter of blood (about the size of a sugar cube). This is five times more viruses in a few drops of blood than there are stars in the galaxy! When viruses take over a cell, they kill it or disrupt it. This is what makes you sick. Your immune system fights the virus, and many of the things it does make you feel sick also. Your body gets fevers because sometimes viruses do not grow as well at higher temperatures. Because the viruses are inside your cells, your immune system has to kill the infected cells before they can make more viruses to prevent the virus from multiplying.

Viruses actually do not make us sicker than bacteria. In fact, you never even know you have many viral infections. We do not have as many problems with bacteria as we used to, because bacteria can usually be treated with antibiotics. Except in a few cases, such as HIV and herpes-viruses, there are no drugs to treat viral infections. We may feel worse with a viral infection than with a bacterial infection, because our only choice is to suffer through it. In major infections, however, bacteria are generally much more dangerous than viruses. There are bacteria that make the most deadly poisons on earth. Also, there are bacteria that are resistant to all known forms of antibiotics. There are only a very few viral diseases that are deadly, such as smallpox, Ebola, and Hantavirus. The biggest danger to viral infections is generally that they will weaken a person to the point that they cannot fight off bacterial infections.

Viruses are fascinating, teetering on the edge of living and nonliving, unable to do anything by themselves but able to completely take over cells they invade. Studying viruses has given us insights into how our own cells work. Because viruses can enter cells, they can potentially be used in gene therapy. There is even at least one virus that slows down cancer. Viruses can be dangerous, but exciting, tiny windows into our own bodies.

Sources:

Fundamental Virology, third edition. ed. B Fields, D Knipe and P Howley. Lippincott-Raven. Philadelphia 1996.

www.virology.net

How Does a Lightbulb Work?

2001-05-15T13:15:00.000-07:00

A light bulb is made from a very thin piece of glass. The glass is heated up and blown into a shape of a bulb. Once cooled, the inside of the bulb is coated with a material that diffuses the light. The filament of a light bulb is made of tungsten. Tungsten is a metal like element that burns in the presence of oxygen. The tungsten wire that the filament is made from is very thin, on the order of 0.0017 inches thick! The filament is made of coiling the tungsten wire around itself, forming a double coil. The ends of the coil are then attached to power leads that are inside the glass base of the bulb. The glass top and bottom are then melted together, the bulb is sealed, and the oxygen is removed from the bulb. Various gases can then be introduced into the bulb. A metal base is added and the bulb is ready to use.

In a normal light bulb an electric current travels through a coiled tungsten wire. Current is carried in a wire by bumping electrons off of the atoms or molecules that make up the wire, like marbles. One electron is bumped which bumps another electron. Electrons do not collect within the wire, but rather one electron is bumped and replaced in the atom by the one that bumped it. This bumping creates energy. The energy is released as heat in the filament and can heat the filament to up to 2500 degrees Celsius! At 2500 degrees Celsius the light bulb emits about 12% of its energy as visible light. Energy is also given off from the bulb as invisible infrared light or heat.

Evidence exists that Thomas Edison was not actually the inventor of the light bulb. In 1878 British inventor Joseph Swan patented the carbon filament light bulb. That following year Edison patented the same carbon filament bulb. As a result of the law suit Swan flied against Edison, the Edison and Swan Electric Company was formed. In 1882 Swan sold his patent to Brush Electric Company. Edison owned Brush, later General Electric, and got the credit for the patents. The light bulb developed by Swan and Edison is based on the same principles as the ones we currently use today. Improvements in the make up of the filaments have been made to lengthen the life of the bulb.

In neon lights, similar concepts are used. Different gases and coatings can be added to the glass to induce different colors.

How Do Sun-Powered Homes Work?

2001-04-15T13:13:00.000-07:00

Most existing buildings, including your home, are powered through an electrical grid.This grid connects all the homes in your neighborhood and all the buildings downtown through wires. At a power plant the wires all come together. A power plant generates the electricity that you use to light, heat, and cool your home. Power also allows you to turn on your hair dryer, your computer, and your microwave.The power that is produced at most of these power plants comes from fossil fuels.

There are three forms of fossil fuels: coal, oil, and natural gas. All three were formed several hundred million years ago, before the time of the dinosaurs. This time period is called the Carboniferous Period and occurred about 360 million years ago. The planet was covered with swamps, trees, and large leafy plants. As the plants died, they sunk to the bottom of the swamps. Over many, many years, these plants were covered with sand, rocks, and other minerals. Eventually, all the water within the plants was squeezed out. The remaining material became coal, oil, or natural gas.

Mining companies take these fossil fuels out of the earth and use them to generate electricity. In order to produce energy, power plants burn fossil fuels. These fuels give us the energy to run our cars and power our homes. However, fossil fuels take millions of years to make. Right now, we are using fossil fuels that were made over 300 million years ago. If we don't conserve the fossil fuels that we have, we may run out!

HAVE NO FEAR! There is an alternative to using fossil fuels. Any guesses?

The sun and the wind! Scientists are discovering more ways to use renewable energy sources such as the sun and wind. Renewable means that unlike fossil fuels, which are limited in energy, these sources will not run out. Another bonus to using renewable resources is that they don't pollute the environment the way fossil fuels do. When fossil fuels are burned, they release gases into the air. These gases can be harmful to the environment and may contribute to individuals' developing cancer or allergies. Renewable resources, like sun and wind, do not have bad side effects. Through science the sun may help us fuel more environmentally friendly homes, cars, and much more.

Little Lions Experiment:

For this month's experiment, you need to talk your parents or an adult family member into taking you to the Clean Energy Expo at Penn State. This event is free and will take place from April 2-3, 2004, at the Bryce Jordan Center. Check it out on the web at http://www.wppsef.org/cee/. Once you are at the expo, visit the Penn State Science Lions booth where you can do some actual hands-on energy experiments!

If you are not able to make it to the expo, search your home for ways to cut down on use of electricity and other resources. For example, figure out ways to conserve water while showering or washing your dishes. Or, research how to start a recycling program in your home, school, or neighborhood.

Resources:

Chapter 8: Fossil Fuels- Coal, Oil and Natural Gas; found at http://www.energyquest.ca.gov/story/index.html .

A Primer on Sustainable Building. Rocky Mountain Institute, 1998.

Dr. Riley with the Penn State American Indian Housing Initiative found at www.engr.psu.edu/greenbuild.

Author:

Science Lions wrote this article with the help of Amy Grommes, a graduate student in Architectural Engineering at Penn State. Amy studies architectural sustainability and works on using straw bales and other "green" (environmental friendly) materials to build homes for the Northern Cheyenne in Lame Deer, Montana. View Dr. Riley's website for more information on this project.

What is Love?

2001-03-01T13:11:00.000-08:00

Valentine's Day is full with heart-shaped candy, cards, and decorations. But, is the heart the only thing involved in falling in love? No. People in love often feel what they describe as a love "high." Professor Semir Zeki and his team of researchers at the University College London wanted to find out what parts of the brain are involved in this "love high." The professor and his team tested 17 young men and women who had fallen in love in the previous six to twelve months. Each of these research participants had their brain scanned. The scans help measure changes in blood flow. These measures were taken as the research participants looked at a photo of their loved one. Measures were also taken when the participant looked at three other photos. These other photos were pictures of individuals of the same gender, but were only friends. The research team noted changes in the blood flow in the brain. There was heightened activity in four areas when the individual looked at the photo of his or her loved one.

The four hot spots were the anterior cingulate, the medial insula, the putamen and the caudate nucleus. The anterior cingluate is the section of the brain that is towards the bottom of the brain. The anterior cingluate is known to be involved with responding to drugs that induce feelings of relaxation. It is associated with happy states, attention to one's own emotional state, and especially social interactions. The second region is the medial insula. This section can be viewed from the top. The medial insula is related to a host of emotional functions. The third and fourth sections are the putamen and caudate nucleus. They are in the back of the brain. The putamen and caudate lie deep in the brain. Both are frequently stimulated when we experience both positive and negative emotions.

Professor Zeki was pretty excited about these findings as he explained: "...we have discovered that this overwhelming state of love--which mobilizes your whole life--is actually controlled by four small areas of the brain." The team also found out what is not activated in the brain by their lover's photos. Some of these regions have been found to be related to sadness and can be overactive when people are depressed.

Little Lion Experiment:

Psychologists are scientists who study the mind and behavior. Psychologists study a variety of parts of the human experience from the functions of the brain to the actions of nations. They study child development to the care of the aged. One tool psychologists use to study the mind and behavior is pictures and a notebook. They use the pictures to ask their patients questions about how they feel and what they are thinking about when they look at these pictures. Cut through the newspaper and some magazines (after people are done reading them) and then ask your friends and family about the pictures. Take notes of their answers and see if certain pictures made more people happy or sad, excited or scared, or any other terms that the participants come up with. Be creative and you will find the brain is creative too.

How Do Airplanes Stay in the Air?

2001-02-01T13:00:00.000-08:00

Flying for the holidays? Or, did grandma fly in to visit you for Christmas? Have you ever wondered--while on a plane or watching one--how a heavy, metal plane flies through the air?

Whether you are scared of flying or not, the answer to this question is a little frightening. Physicists and aeronautical engineers continue to debate the basic mechanics of flight. This is even more suprising when you consider that the Wright brothers invented the plane over 100 years ago! In spite of the debate, everyone agrees that flight boils down to physics. Yes, this means that no invisible strings are hanging from space!

Most will go on to explain that a plane's ability to fly results from air traveling faster over the more curvaceous top surface of the wing than under the flatter bottom surface. The quicker a fluid like air moves, the less pressure it exerts. This phenomenon is known as Bernoulli's principle and was discovered by Daniel Bernoulli, an 18th century Swiss mathematician. The principle helps us to understand how slower moving air below the wing exerts more pressure on the wing than the faster moving air above it. This results in an upward force called lift. Lift pushes the aircraft upward against the downward pull of gravity.

This principle is well-accepted and accurate, but it does not help us to understand why the air flowing over the wing moves faster. This lack of explanation causes confusion among physicists and aeronautical engineers. One of the leaders in helping to explain this phenomenon, Jef Raskin, actually started his research by arguing with one of his middle school teachers. He argued that this principle didn't make sense because he had seen planes fly upside down. Raskin felt that Sir Isaac Newton's laws of motion were a better explanation, as "a wing is just a device for forcing air down." According to Newton's third law, for every action there is an equal and opposite reaction, so the downward force that the wing applies to the air produces an upward force of the air on the wing. The amount of air directed downward depends on the angle of the wing (the angle of attack) and not the shape of the wing. This would help explain why a plane can fly upside down.

Although Newton's law helps to explain how planes can fly upside down, most believe that both Bernoulli and Newton help to explain flight. They also recognize that curves on the top of the plane are important and without them an airplane may stall and fall.

Flight is a fascinating science, and many aspects of why we can fly are still under debate. Start asking your teacher questions and maybe you will help get some of the debate of flight mechanics off the ground!

Source: Chang K. "What Does Keep Them Up There?" New York Times. 9 December 2003.

Little Lion Experiment

An important concept in understanding how objects move is gravity. Gravity is the tendency of matter toward some attracting body, particularly towards the center of the earth. To understand the effect of gravity or a flying objects attraction to the ground, drop varies objects such as a piece of paper, a shoe, a book, and a feather from a table. Guess, watch, time, and test which object falls the fastest.

Gravity adds weight or force - an equal amount to each object. But, gravity increases the force or speed of motion on the heavier objects. Thus, the heavier objects such as a shoe or book would beat a piece of paper or feather. You can also feel this principle at work when you slip on ice with and without your book bag! Be careful this winter!