Staying Dry Underwater
		Materials: A basin of water A cup A handkerchief

Procedure: Place the handkerchief in the cup, pushing it all the way down to the bottom. Invert the cup and push the cup under water (completely). Bring the cup back up and pull the hankerchief out - it should be still dry.

Explanation: As you push the cup under water you catch a pocket of air in the cup. It cannot escape unless you tilt the cup (because air is lighter than water and therefore can only travel up - but it is blocked by the cup). The further down you push the cup, the more the water will compress the air and it will therefore slowly approach the handkerchief the deeper you go.