Mom gave Ethan an electronic snap circuit kit by Elenco this last Christmas. Very fun, very educational, for ages "8 to 108." Anyway, we are doing project #246, a 2 finger touch lamp which consists of an npn transistor (npn?), a couple of resistors, an LED diode, power source and a kiss, or bodily bridging of contacts, if you will. Ethan came up with the idea of using a kiss.
If you have a child who is interested in the physical sciences, I recommend this kit. It's as interesting for parent as for child. The project illustrations make it simple to build any circuit listed. If you don't believe, I can even build a lie detector to prove it.