Your son, Kevin is 12.
Kevin isn't that much into the theory of science, but he loves labs and playing with practical applications.
You've been having trouble with one of the props you use for your classes, so you brought it home Friday to check the wiring. Kevin was specifically told not to play with it, until you said it was okay.
You just got home. Looked at him, and asked.
Kevin says, "No, Dad. I haven't been playing with your Van de Graaff generator. Why?"