This trick looks like magic, but it's science
Try this science experiment with your child: Place a penny on a sheet of paper. Set a clear glass of water on top of the penny. Can your child see the penny? Next, cover the top of the glass with a saucer. The penny disappears! Explain that we see objects when light rays reflect off them into our eyes. But the light reflecting off the penny has to pass through air, water and glass, which makes it bend. The saucer blocks the bent light ray from reaching your child's eye, and the penny seems to disappear.