Published: 2008-11-05 09:57:35
Updated: 2008-11-05 09:57:35
Posted November 5, 2008 9:57 a.m. EST
By Lisa Wells
MIKE MOSS SAYS: Lisa, A couple of my favorites are simple demonstrations of the power of air pressure. The simplest, and one that doesn't require much at all in the way of equipment or preparation, involves a small juice glass, a bottle of water and a piece of thin card stock (something like an index card will work, and I've had good luck with slightly stiff coupons or the kinds of mailers that many politicians have sent around in recent week, cut to a square that's a little larger than the opening of the glass. I just talk a little about air pressure and how most of us don't really notice it's even there unless we drive up and down a mountain or fly, but that it's a powerful force. I then put the piece of paper over the empty glass, hold it upside down dramatically, let go of the paper -- and it falls off. Student reaction is usually something like, "of course." I then fill the glass almost to the top with water and ask students to think about which is heavier, water or air (water by a long shot!) - then I put the paper over top of the glass, turn it upside down and likewise let go of the paper - there are usually some gasps from the group who all expect water to splatter on the floor, when instead the air pressure (about 14.7 psi against the paper) more than balances the weight of the water and holds it inside the glass. I do recommend you practice a time or two at home!
I'm pretty sure there are some teaching books with other weather and atmosphere-related classroom experiments that you can probably turn up with a web search or a visit to a textbook supply store. Good luck! Also, you might find the "tornado in a bottle" more fun if you place a few "Monopoly" houses inside!
If anyone reading has some additional ideas or something you've seen that really caught your attention, let us know in comments...