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?

What Causes Lightning And Thunder?

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:

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