Air is a real substance even though you can't see it. A flat sheet of document falling downwards pushes against the air in their path. The air forces back from the paper and slows its fall. The crumpled document has a smaller surface pushing against the air. The air doesn't push back as strongly as with the flat piece, and the ball of paper falls faster. The spread-out wings of a paper aeroplane keep it from falling quickly down to the ground. We say the wings give a plane lift. The secret lies in the shape of the wing. The front edge of an aeroplane's wing is more Avion En Papier Planeur rounded and fuller than the rear border. Which usually paper falls to the ground first? What seems to keep the flat sheet from falling quickly? We live with air everywhere. Our planet earth is between a level of air called the atmosphere. The atmosphere stretches hundreds of miles above the surface of the world. Take two sheets of the same-sized paper. Crumple one of the p...