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?

Why Does Newspaper Turn Yellow?

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

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

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

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

Little Lion Experiment:

Items Needed:

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

Steps

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

Questions:

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

How Does the Sun Affect Our Lives?

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

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

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

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

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

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

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

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

Little Lion Experiment:

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

Items Needed:

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

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

Questions:

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

How Do Leaves Get Water from Roots?

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

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

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

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

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

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

Little Lion Experiment 1:

Items Needed:

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

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

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

Little Lion Experiment 2:

Items Needed:

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

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

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

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

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

Why Do Leaves Change Color in the Fall?

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

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

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

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

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

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

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

Little Lion Experiment 1:

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

Items Needed:

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

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

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

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

Little Lion Experiment 2:

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

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

References:

• http://www.sciencemadesimple.com/leaves.html#autumn_leaves_science_project
• http://blogs.cjonline.com/index.php?entry=382
• http://portlandme.about.com/cs/fallfoliage/a/leaveschange.htm
• http://www.esf.edu/pubprog/brochure/leaves/leaves.htm