This week's experiment came from Diane in South-central Pennsylvania. She and her son were discussing ceiling fans, and how they make you feel cooler. Do they actually cool the room?

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The Wonders of Ice

Explore why ice is one of the strangest solids we know of.

This week's experiment came from a conversation that I had with a friend about how things react to hot and cold. This is an easy way that you can observe what is going on as you change the temperature of some air. You will need:

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This week's experiment should be familiar to any of you that have ever cooked pancakes. As my mother taught me, and as you will find in most cookbooks, in order to tell if the skillet is hot enough for pancakes, you dip your fingers into some water and then shake a few drops onto the skillet. If the drops just sit there or if they hit the skillet and boil, then it is not hot enough. As the temperature of the skillet increases, you reach a point where the drop of water seems to bounce and glide around the skillet. Then you know that the skillet is hot enough for pancakes. This is called the Leidenfrost Effect, and that is what we want to observe now.

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This experiment was sent in by Leilah, an 11 year old list member from Indiana. It is exactly the kind of experiment I like, because it is simple, it makes you think, and it’s interesting enough to get you to actually try it, instead of just saying, "Wow, I'll have to try that some time."

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This project has science fair potential.

We are used to thinking of things as falling into the basic groups of solids, liquids, and gases. (In another experiment we will discuss a fourth state of matter, plasma.) In this experiment, we will examine a substance that sometimes acts like a solid and at other times acts like a liquid.

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I have seen many different ways to show how changes in pressure can form clouds, but this is the easiest yet.

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There are many things that will float on water: pieces of wood, wax, Styrofoam, and many other things. They float because they are less dense than the water. Now for the question. Can water float on water? Is there a way to make water less dense?

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Sometimes the right answer is not the only answer.

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This week's experiment came to me from my good friend Bob Cox. He told me about the trick and wanted to know why it worked. It took some thought and testing to come up with a theory of what is happening and then several e-mails to experts to confirm that I was on the right track. For this week's experiment, you will need:

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Which will go out first, the tall candle or the short one?

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The answer to the last video's challenge.

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Can you lift an ice cube out of a glass of water with a string? Try it and see.

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Make a tasty snack while learning about the science of butter.

It is amazing how many books get this one wrong!

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