THINGS REQUIRED :
Sheet of typing paper
Hold a 21 x 28 cm sheet of typing paper high above your head. Use both hands to grasp the paper. Let it go. The paper will scoot in various directions and probably turn over.
Now make two folds in the side of the paper, first, 2.5 cm inward, then, 2.5 cm again.
Hold the paper over your head, but make sure that the folded edge is at the front, and on the underside, of the sheet. Gently push the paper as you release your grip. The paper will not turn over and glide for some distance before falling to the ground.
As the plain sheet of paper falls, the force of the rushing air over it causes differences in air pressure over different parts of paper. The front end tilts up, and the paper may move in a topsy - turvy (upside down) fashion. However, by folding the edge, you increase the weight that is at the front, and this weigh balances the upward force of air, causing the paper to glide smoothly without flipping over, Airplane wings are shaped like this also - they are a little bit heavier in front than they are in the rear - which helps make ride a smooth one.