This is a really neat trick! It's almost like magic! You can amaze and surprise your family and friends!

(Caution: Do this activity away from other students, and be sure no one is in front of the stick.)

Place a yardstick, a slat from a wooden crate, or some other very thin piece of wood about 1 yard long and 2 inches wide on a table, allowing about 1 foot to extend over the edge. Hit the end of the stick with your hand, just hard enough to knock the stick off the table. That wasn't very exciting or surprising, was it?

(When you do this trick at home, be sure you aren't using your mom's very favorite yardstick. Otherwise, you can get into trouble!)

Now place the stick in the same position, and lay an open section of newspaper over the part of the stick that is on the table.

Strike the end of the stick just like you did the first time. Woh! That is the end of that stick! How can it be that it broke?

Stay tuned, and you may find out.

Before we find out the whole truth, get another stick just like the first one. Fold that newspaper into a small bundle, about 6 inches long by 4 inches wide, and tape the edges, so that the bundle lies flat. Remember, this is the same newspaper you used before, so the results should be the same. Right? Well,...

Put the newspaper bundle onto the new stick, and hit the end that hangs over the edge of the table.

How is it that the stick did not break? Think about it, and make some guesses.

So now we'll do it all again. The only thing we will do differently is that we will mark off one side of the open newspaper into 1 inch squares before placing it on the stick and striking the end of the stick.

We won't need another stick to replace the second one we broke, because we can figure it out without doing the other part a second time. We'll just fold the paper into a bundle like we did before. Look at it. Notice anything on which any of you might want to comment?

Okay, open up the paper, and count the squares. Fold the paper into a bundle and count the squares you can see. What the squares tell is that there are a certain number of square inches of surface on the opened-up newspaper. There are many less square inches of surface on the folded paper bundle.

The name of the game is "air pressure," which means how much the air weighs. At sea level the weight of the air on 1 square inch of surface is about 15 pounds.

So when the paper is open, how many pounds of air pressure (weight) are pushing down onto the paper? When the paper is in a bundle, how many pounds of air pressure are pushing down onto it?

Next, mark off a piece of notebook paper into 1 inch squares, then draw an outline of your hands on the paper and calculate how many pounds of air are pressing down on your hands.

Estimate how many 1-inch squares could fit on the outside of your body and how many pounds of air you think your body
supports.

If you wonder why you are not crushed by all this pressure, remember that our bodies, like most objects, have air in them, and this air pushes outward with the same force that outside air pushes in. When the forces are equal, we cannot feel the pressure. When they are unequal, we do feel the pressure.

You can relate the sensation of your ears "popping" to this experience. Have you ever driven up into the mountains? Or down from the mountains into the lowlands? The air in higher altitudes is thinner than at sea level, and as you ascend or descend, the pressure in your Eustachian tubes is different from the outside air pressure. We all know about chewing gum when this happens. How on earth does that help?