Want to get a kid interested in these and how they work? Let the kid play with a slot car set and explain that an electromagnetic motor is responsible for making that racer zip around so fast. To find out if a kid has that spark that could lead to a career in engineering or the sciences, exposing them to cool gadgets such as slot cars and watching their reactions will let parents know if they have an interest in such things.
Hey, we need more scientists and engineers in the world. Figuring out whether a kid could follow those paths early in life may be doing him or her a favor.