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

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?

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

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?

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?

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

1. Method 1: Put one onion into the refrigerator. After 30 minutes, take it out and cut the onion.
2. 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.
3. Method 3: Put a lemon slice in your mouth. Then cut the onion (keeping your mouth open)
4. Method 4: Put a bread slice in your mouth. Then cut the onion (keeping your mouth open).
5. 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?

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

1. Fill one bowl with warm water and the other bowl with cold water.
2. With the gloves on, add one tablespoon of your soap to each bowl.
3. Use the tablespoon to mix the soap into each bowl for 30 seconds.
4. 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?

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

1. Cut squares into the center of each index card. Try to make all the squares the same size (e.g., about 2'' by 3'').
2. 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.
3. Write down the locations on the index cards so that each index card has a different location on it
4. Write the starting date on each index card
5. Cover the window on the index card with the tape so that the stick side up or out.
6. Attach string to each index card, and then hang the cards at the appropriate locations.
7. 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?

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?

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?

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

1. Put each liquid in its own glass.
2. Drop one of each solid material (i.e., ice cube, small rock, small magnet, quarter) into each glass.
3. 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?

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

1. Run water over the inner surface of the roll until it is wet but not soggy.
2. 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
3. Rotate the tube until it is coated with the pepper.
4. 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?

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?

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

1. Fill the bowl with about an inch of water.
2. Turn the empty plastic cup upside-down and squeeze it until it bends inward.
3. Place the bent cup in the water.
4. 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?

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?

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

1. Fill the bottle with equal parts water and rubbing alcohol until the bottle is 25% full.
2. Add a few drops of food coloring.
3. Put the straw in the bottle, but don't let it touch the bottom.
4. 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).
5. 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?

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

1. Fill each of the plastic bags with three cups of uniformly moistened soil.
2. Thoroughly wet each material to be tested and blot away any excess water from the surface.
3. 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.
4. 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.
5. Use the permanent marker to label each bag with the date, the material being tested, and soil type.
6. Use the permanent marker to label each bag with the date, the material being tested, and soil type.
7. 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

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?

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?

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:

1. 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.
2. 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.
3. Repeat steps 1-2 for 7 days.
4. 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?

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:

1. Rip or cut the red cabbage into pieces (they should be small enough to fit in the pot).
2. 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).
3. Add the shredded cabbage to the boiling water and let it cook for approximately 10 minutes.
4. 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?