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?