Making a can that "magically" rolls back toward the person who sent it away and designing a roller coaster track for marbles are two science projects displaying kinetic energy. Kinetic energy is the type of energy that is expressed in movement, either of a body or of a system's particles.
Making the magic can requires a coffee can, a nail, a 9-volt battery, two paper clips, tape and a rubber band. Make a hole in the bottom and lid of the can. Tape the battery to the center of the rubber band, make sure that both sides of the rubber band are attached to the underside of the battery. Put the loops of the rubber band through the two holes before clipping and taping them in place. Tighten the rubber band If the battery touches the side of the can when the can rolls. As the can rolls, the band twists, and the can slows down. When the can stops, the band starts to untwist, and the can rolls backward. The kinetic energy converts into potential energy inside the rubber band and then back into kinetic energy as the can moves backward.
Foam pipe insulation and masking tape make a roller coaster track suitable for marbles. Running the marble down the long hill shows the transfer from potential to kinetic energy.