This experiment comes from a suggestion made by B. Eschner. It started with his observations as he washed a plastic bag. It developed into a demonstration of water pressure, which then turned into a wonderful explanation of why things float. The more I played with it; the more I liked it. I hope you will have as much fun (and learn as much) as I did.
This is another of those fun bits of science that many of us think we understand until we really start to look at it, or even better, try to explain it to someone else. Then we reach a point where it becomes obvious to ourselves, and to our audience, that we don't understand it as well as we thought we did.
This experiment got its start while I was reading Craig F. Bohren's "What Light Through Yonder Window Breaks." It is a book on atmospheric physics, and is written so that you don't have to be a physics professor (or even a physics student) to understand and enjoy it. He writes about the dew that forms on your house windows in the winter, which made me think of other questions about dew drops.
This experiment is another old classic which is still a lot of fun. Now that I think of it, it seems that most of the science tricks I did as a kid have become OLD classics, but this was already an old classic even way back then.
This experiment came from Diane in South-central Pennsylvania. She and her son were discussing ceiling fans, and how they make you feel cooler. They wanted to know if the fan actually cools the room, or does it just feel that way?