For this experiment, you will need:

1. several balloons - 7 inch or larger balloons work very well
2. a faucet to fill the water balloons
3. an area where you can make a mess with water

Start by filling a balloon with water. Tie it off, and then find a nice, hard surface where it is OK to make a mess. Hold the water balloon about shoulder high and drop it. It will probably break when it hits the ground.

Next, fill a balloon half full of water and then (holding the neck of the balloon to avoid making a bigger mess) inflate the balloon the rest of the way with air. If you are not careful, you will get a face full of water, but that is half the fun. Now, tie off the half and half balloon. Hold it at arm's length and drop it. Unless you drop it on something sharp, it will not pop, even though it is falling just as fast as the one that was filled with water. (Remember that, ignoring air resistance, gravity causes different objects to fall at the same rate, regardless of weight.)

What is different about a full water balloon and a half and half balloon? Obviously, the air, but why would that make such a difference? Air is compressible, while water is not. When you drop the half and half balloon, the air inside is compressed, absorbing part of the shock. This lessens the stress on the balloon and keeps it from popping as easily. Play with this half and half balloon and you will see that it can take quite a bit of impact and still not pop, unless you accidentally throw it at your little brother, but of course, I would never do that.

Have a wonder-filled week.

Place two quarters on the table in a stack, with another stack of two quarters far apart enough so that they will support the glass if it is turned upside down. Place the dime on the table between them. Turn the glass upside down and place it onto the two quarters.

Now comes the trick. The dime is under the glass. You want the dime to be outside the glass, but you are not allowed to touch or move the glass. You cannot stick anything under the glass. Because the glass is supported by the other coins, there is just enough room for the dime to slide under the edge and come out to you. Easy, right? All you need to do is convince the dime to do that. How?

It is really quite simple. Pretend that the table itches just in front of the glass. Use your fingernail to scratch the tablecloth, just as if it itched. Watch the dime carefully as you do this. The coin begins to slide towards you. Soon, the dime will be out from under the glass.

How does this work? The trick is the similar of the old trick of jerking the tablecloth out from under the dishes. As you scratch the cloth, you stretch it towards you. This moves the coin forward slightly. When you lift your finger to scratch again, the cloth snaps back. Because this movement is so quick, the coin does not move back with it. Inertia causes the coin to resist the rapid change in movement. With each scratch, the coin moves forward with the slower movement of your scratch, but is left behind with the faster movement as the cloth snaps back in place.

To make the illusion better, make a big deal about calling the coin, just as if you were calling a pet. Once you have impressed your friends with your magic trick, you can impress them again by explaining the science behind it.

Have a wonder-filled week.

To find your directions, you will need:

1. a sunny spot on the ground
2. one stick, about 12 inches long
3. two short sticks or rocks
4. a flashlight or lamp

Find a flat, bare, sunny patch of ground. Remove any stones, leaves, etc. Place the long stick into the ground in the center of the sunny spot, so it will cast a long shadow. Place one of the short sticks in the ground to mark the end of the long stick's shadow. Now all you have to do is wait 15 or 20 minutes. Do some bird watching and have a snack. You did pack the freeze-dried ice cream, didn't you?

After about 15 minutes, look to see how things have changed. You will find that the shadow of the long stick has moved. Use the second short stick to mark the new position of the shadow. Draw a line on the ground to connect the two short sticks. This is your east-west line. The first stick will be at the west end, and the second will be at the east end of the line.

Next, draw a line perpendicular to the east-west line to form an "X". This is your north-south line. If you are at the west end of the east-west line, facing east, north is on your left and south is on your right. I find that if I visualize a map of the world, then once I know east and west, it is easy to remember north and south.

Understanding the Science

In the morning, the Sun rises in the east, moves across the sky and sets in the west, right? Well, it appears to. Technically, the Sun stays in the same place, relative to the Earth. It is the rotation of the Earth that makes the Sun appear to move. Even so, we can use the apparent movement of the Sun to find our directions.

As the Sun seems to move from east to west, what would happen to the shadows of objects? Place an object on a flat surface and use a flashlight or lamp to give it a shadow. Move the light and notice how the shadow moves. When you move the light in one direction, the shadow will move in the opposite direction. That is what we need to know to find our directions.

As the Sun appears to move west, the shadow of the stick will move to the east. The line connecting the original end of the shadow with the new position will show you east and west. Since the Sun seems to be moving from east to west, the shadow will have moved from west to east. The original marker is the west end of the line. The new position is the east end. Simply draw in the north/south line and you have your directions.

But what about moss? Have you ever heard that you can find north by looking at the moss on trees? There is an old saying that moss grows on the north side of a tree, but actually moss usually grows on the shady side of a tree, not liking to grow in full sunlight. In the Northern Hemisphere, the north side of a tree is usually shady, but it is not uncommon to find trees with moss on all sides. In the Southern Hemisphere, the moss would tend to grow on the south side of trees. In dry areas, there may not be any moss at all. If there is a clearing to the north, then moss may be on the south side and not on the north side, so don't rely on moss to help you find your way. Instead, stick with the Sun.

Have a wonder-filled week.

For this experiment, you will need:

1. a two liter, plastic soft drink bottle
2. a medicine dropper
3. water
4. a large glass of water

Place the dropper in the glass of water. Squeeze the bulb to let some of the air bubble out. When you release the bulb, water will move in to replace the air you removed. If you release the dropper, it should just barely float in the water. If it floats too high, squeeze it to remove more air. If it sinks, then squeeze out a drop of water and let it take in some air. Then try it again. Keep trying until you reach the point where it just floats.

Fill the two-liter bottle to the top with water. Place the dropper into the bottle and put on the cap. Now, gently squeeze the bottle and the dropper will sink to the bottom. Release the bottle and the dropper rises back to the top.

Understanding the Science

Why does it do this? To understand, we need to know about compressing things and about why things float or sink.

First, lets talk about compression. Generally, gases are easy to compress, while solids and liquids are not. Our soda bottle contains water and air (the air inside the dropper.) When you squeeze the bottle, the water does not get any smaller. Instead, the air inside the dropper is compressed, taking up less space.

Next, we need to understand floating and sinking. If we put an object, say for example, a scoop of ice cream, into a liquid, maybe a nice glass of soda, will it float or sink? All we have to do is compare the density of the object to the density of the liquid. If the object is denser than the liquid, it will sink. If it is less dense, it will float.

OK, then what in the world is density? While it sounds like weight, but there is more to it than that. For density, we compare the weight of a specific sized object with the weight of the same volume of the liquid. So if one cubic foot of ice cream weighs less than one cubic foot of soda, then it is less dense, so ANY sized scoop of ice cream will float in the soda.

On the other hand, if one cubic foot of the ice cream weighs more than one cubic foot of the soda, then it is more dense. That means that any sized chunk of the ice cream would sink.

OK, now lets combine those ideas to understand the Diver. Before you squeeze the bottle, the combination of the dropper and the air weigh less than the same amount of water, and so it floats.

As you squeeze the bottle, the water will not compress. Instead, the air bubble inside the dropper gets squeezed, making it smaller. Now the dropper and bubble still weigh the same, but they take up less space. When the bubble gets small enough, you reach the point where the dropper and bubble weigh more than the same amount of water, and, your Cartesian Diver will sink. When you release the bottle, the air bubble expands back to its original size. Since your Diver takes up more space now, it floats again.

With practice, you can use this for a fun, scientific magic trick. Hold the bottle, and tell the dropper to sink. As you do, gently squeeze the bottle. Then tell it to float, and release the pressure on the bottle. You can make it appear that the dropper is obeying your commands. Then explain the science behind the trick and your audience will be even more impressed.

There are several ways to build on this experiment. As we were taping this video, we noticed that the droppers began to sink without me squeezing. It turned out that a high pressure front was moving through Jacksonville, and the increased air pressure was squeezing the bottle. With several droppers, you could make a barometer for measuring air pressure. Temperature will change things too. As the air in the dropper gets warmer, it will expand. As it gets colder, it will shrink. Once again, this could be used to make a thermometer, telling the temperature by which droppers floated and which ones sank. You can find those in some specialty stores. I even thought for a moment of trying it with ice cream in a full bottle of soda, but that would give results like the famous Mentos experiment, causing a fountain of soda in your kitchen. Not a good idea.

Have a wonder-filled week.

Place the candles on the cake, grouping them very close together. You may want to put some ice cream beside the cake. It does not make the experiment work better, but it does make the experiment more enjoyable. Light the candles. As your friend prepares to blow out the candles, have a lit match or lighter ready.

As soon as the candles are blown out, you will see a column of white smoke rising from the candle. Bring the flame of the match or lighter into this smoke and it will flash back, relighting the candles..

Understanding the Science
Why does this happen? To understand, we need to know that there are different kinds of smoke. While a candle is burning, any smoke that it produces will be black. You might have noticed this black soot when you tried heating the water in your water balloon in one of the previous experiments. The black smoke is made up of tiny particles of carbon that are not burned up in the flame.

When you blow out a candle, you get smoke that is white instead of black. This white smoke is made of the unburned vapor from the hot wax. The melted wax has gotten hot enough to vaporize and form a flammable gas that would normally burn to produce the flame. Since it is not hot enough to catch fire, instead it rises from the candle. The vapor in this white smoke is very flammable. When you bring the match into the vapor, it burns. If the wax in the wick is still hot enough, this added heat will be enough to relight the candle.

You don't have to wait for someone's birthday to try this, but you really should have the ice cream, and maybe a little chocolate sauce. As long as you have permission and an adult present to help, you can do this experiment anytime.

Have a wonder-filled week.

Use the scissors to cut 2 strips of paper about 11 inches long and 2 inches wide. Lay both strips on the table and print the letter “A” at both ends of each strip. Then turn the strips over, with the A side down, and print the letter “B” at both ends of each strip.

Pick one of the strips to start with. Bring the ends together to make a circle, matching A to A, and tape the ends together. Pick a starting point on the inside of the strip and use the pen to draw a line down the center of the strip. Continue until the line connects with itself and you have a circle all the way around the inside of the strip. OK, no surprises there.

Now, we will do the same thing with the other strip, but this time twist one end, so that the "A" on one end matches up with the "B" on the other. Now, you should have a loop that is twisted in the middle. Use some tape to fasten the two ends together.

Once again, use the pen to draw a line down the middle of the strip. Keep drawing until the line connects back to itself. Do you notice anything unusual this time? By the time the line connects, you have drawn on both sides of the strip, inside and out. The Mobius strip really has only one side! The inside is part of the outside.

Not only does it only have one side, it also only has one edge. Pick a starting place on one edge. Use the pen to draw a line along the edge. Keep following the edge until you get back to your starting point. You will have a line along both edges of the strip, because they are part of the same edge.

For the next bit of strangeness, we are going to use the scissors to cut each strip in half. Don't cut through the strip. Instead, we are going to cut along the line that we drew down the center.

When you cut the first strip, you wind up with two separate loops. Again, no surprise there. What happens when you cut the Mobius strip? You get one big loop, with a twist in it. Why?.

Understanding the Science
Well, remember that the Mobius strip only had one edge, but that edge was twice as long as the strip, going down the left and the right part of the strip. When you cut it down the middle, you give it a second edge. Both halves of your cut are again part of that second edge, so it is also twice as long as the strip. That gives you a loop twice as long as the original strip, which has two edges. It is no longer a Mobius strip. If you draw a line down its center, you will see that this larger loop actually does have two sides and two edges.

For even more strangeness, cut that loop in half again. What did you get this time? You’ll have to try it to see. You can keep exploring with different variations. Try making your original cut near one edge instead of in the middle. Try give the original strip 3 twists instead of one.

Do Mobius strips have any uses? They sure do. Often, conveyor belts are Mobius strips, so the wear and tear is distributed over the entire surface, making them last longer. Typewriter ribbons (remember those?) were Mobius strips, letting them get more use from the ribbon. They are also used in continuous loop tape recordings, letting you use a shorter tape and get twice as much recording from it. If only someone would invent Mobius ice cream, so you could fit twice as much in your bowl.

Have a wonder-filled week.

Select an orange. Look at the end where it was attached to the tree. You should see a small button shaped piece that is greenish brown in color. Use your fingers to carefully remove this. Underneath, you will see that there is now a small indentation. Looking closely and you will see a ring of tiny dots. This is where some of you might need a magnifying glass. It will look almost as if someone had used a needle to punch a circle of holes, near the outer edge. Count the dots and remember this number.

Now, slice the orange and count the number of sections. You will find that there are the same number of sections as there were dots. Using this method, you can accurately predict the number of sections inside an orange before it is peeled. Be sure to practice a couple of times before you try this in front of an audience. By counting the dots beforehand, you can pretend to be determining the number of sections by listening to the orange, smelling it or even by spinning it on the table. Once you make your prediction, slice the orange and show that you are correct.

Understanding the Science
How does this work? The orange is divided up into sections, which are pretty much separated. There has to be a way for all the sugar, juice and other yummy stuff to get into those sections. Tiny tubes inside the tree bring all that wonderful stuff to the orange. Since the sections are not connected to each other, each must have its own tube. Count the tubes and you count the sections.

Once you amaze your friends by predicting the number of sections, you can amaze them again with your scientific knowledge by explaining how you knew. This lets them go on to amaze their friends, getting even more people interested in science. If you are ambitious, you might examine lemons, grapefruits and other citrus fruits to see if this works with them as well. When you are finished, look up a good fruit salad recipe and enjoy yourself.

Have a wonder-filled week!

Blow up one of the balloons and tie it off. Light the candle. Now, what do you think would happen if you held the balloon in the candle flame? Lets try it and see. Carefully, hold the balloon just at the top of the candle flame. BANG! Just as you probably predicted, the balloon pops and it blows out the candle.

Now, lets try that again, but this time with a twist. Instead of filling the balloon with air, lets make it a little more fun. Lets try the experiment with a water balloon! Carefully stretch the mouth of the balloon over a water faucet and slowly fill the balloon with water. Then blow in a little air and tie it off.

At this point, work over a sink or outside, just in case things don't work as they should. Once again, light the candle, and hold the balloon over the candle, just at the top of the flame. What happens? You probably expected the balloon to pop, getting you wet. Instead, the bottom of the balloon turned black, but it did not pop. Why?

Understanding the Science
Water is very good at soaking up heat. Because the balloon is very thin, heat energy passes through it quickly heating the water on the inside. As the water near the flame starts to get hot, it rises, letting cooler water take its place to soak up more heat. This process lets the water balloon absorb a tremendous amount of heat without popping.

The black stuff on the balloon is the element carbon. It did not come from the balloon. Instead, it was deposited by the candle flame. The balloon has not been burned or damaged.

The idea of absorbing heat to control it is a very useful idea indeed. Firefighters use it to protect themselves while they are fighting fires. The radiator in your car absorbs heat from the engine to keep it from overheating. Heat sinks in computers absorb heat to protect delicate circuits. The idea even applies to ice cream, which absorbs the heat from hot fudge sauce, cooling it enough so you can eat it without burning your mouth.

Have a wonder-filled week!

Hold the basket ball about shoulder high in one hand and the tennis ball at the same height with the other. Drop both at the same time. If both are fairly new and fully inflated, they should bounce about the same height. OK, nothing strange about that.

Next, use the tape to make a round, raised collar on the basketball. This is going to help you balance the tennis ball on top of the basketball. It does not have to be fancy. Just a ridge of tape in a circle that will fit the bottom of the tennis ball.

Hold the basketball out at the same height as before, with the tape ring at the top. Place the tennis ball into the tape ring. It should balance there. Now, before you drop it, think about what you expect to happen. Then drop the balls.

Understanding the Science

What happened? The tennis ball bounced VERY high. Why did that happen?

When you were holding the basketball and the tennis ball, they had potential energy, the energy of position. When you released them, that potential energy was changed into the energy of motion. In other words, they fell. When the basketball hit the ground, its momentum compressed it, flattening the bottom. The same thing happened when the tennis ball hit the basketball. Their energy of motion was changed into compressed mechanical energy, much like squeezing a spring.

Then the compressed mechanical energy was changed back into the energy of motion. As the basket ball bounced, it bumped into the tennis. That impact transferred some of the energy of motion from the basketball to the tennis ball. The basketball was left with less energy of motion, so it did not bounce as high as it did the first time. The tennis ball wound up with a lot more energy of motion, so it bounced very high.

What do you think would happen if you reversed the two balls, putting the basketball on the top? How much higher would the extra energy from the tennis ball lift it. What if you used a heavier ball instead of the basketball? Or a ping pong ball on the top? There are all sorts of combinations to try, and you will be surprised how much you learn while you are having fun.

Have a wonder-filled week!

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Even now, ten years and hundreds of weekly experiments later, this is still my favorite way to demonstrate the science of inertia. The demonstration is dramatic enough to make people tense in anticipation, even if they understand the science and have seen it done a hundred times. The science is simple enough for young students to understand, and with practice, even a first grader can successfully perform the demonstration.

You will need:

- a piece of cloth or sheet of newspaper

- two heavy coffee cups (cheap ones in case you break them)

- two saucers (the same thing goes for these)

- a smooth table top

If you are using a piece of cloth, be sure that it is smooth and that the edges have not been hemmed or sewn. You don't want anything that could catch on the bottom of the dishes. If you don't have a piece of cloth available, try using a sheet of newspaper. Be sure to have several sheets available, because they tear after one or two tries, and you will probably want to try this several times.

Lay the cloth or paper on the table, with about half of it hanging off the edge. Place one of the cups on the cloth, about six inches from the far edge. Grasp the hanging end of the cloth firmly. Now comes the part where you have to trust me. If you pull on the cloth gently, the cup will move with it and fall off the table. To get the cup to stay in place, you must jerk the cloth very quickly, downwards and away from the table. Use one quick jerk to pull the cloth completely out from under the cup. If you do it quickly enough, the cup will hardly move.

Understanding the Science

Why did it work? The cup stays in place because of inertia. Inertia causes things that are sitting still to continue sitting still until something pushes or pulls on them with enough force to make them move. The heavier an object is, the more push or pull it takes to overcome their inertia and get them to move.

If you pull the cloth slowly, friction between the cup and the cloth transfers enough pull to move the cup. If you pull the cloth quickly, the cup's inertia causes it to slide on the cloth, letting the cup sit still as the cloth is pulled away.

Now, lets make it more exciting. Put the cloth back on the table and place a saucer where you put the cup earlier. Place a cup on the saucer. Stack the other saucer on top of the cup, and put the other cup on top of that. Now you should have a tower, with a cup sitting on a saucer, sitting on another cup, sitting on another saucer, sitting on the cloth.

Do you think you can pull the cloth out from under it now? Try it, again using a very quick pull. You will find that it is even easier than with the single cup. The more weight you have piled up, the more you have to push or pull to overcome inertia. That is why light, plastic cups don't work well, unless you put something heavy in them. To really impress your friends, use a glass filled with water. The water makes the glass heavier, making the experiment easier. Just be sure to practice a few times someplace where it will be easy to clean up the mess, just in case.

Have a wonder-filled week!