A rubber ball bounces because it is elastic. An elastic substance is made of molecules that do two opposite things: They give when they are pushed, but they also resist being pushed. When a ball hits the floor, the blow flattens it a little. But rubber molecules resist. They push back against the floor. And up goes the ball into the air again, as round as before. You are made of elastic material, too. Think what you would look like if the molecules in your body didn't resist when they are pushed around!
