glass of water with just an ordinary piece of cardboard. Here's how to do it.
DIRECTIONS: Fill a glass halfway with water. Now take a piece of cardboard cut several inches wider than the glass and set it on top of the glass. Holding the cardboard in place, turn the glass upside down, so the water is resting on the cardboard. You'd think that if you took away your hand, the water would push the cardboard out and the water would spill, but try it.
WHY IT WORKS: Turning the glass over creates suction, which holds the cardboard in place. If you move the cardboard slightly, the seal will probably break--something to keep in mind if you're performing the trick in the living room.
