Our (probably 10+ year-old) baby monitor died recently, and Mike took the opportunity to give the kids an electronics lesson. They talked about hooking up LED lights, and saw where the speaker, antenna, and microphone were, but mostly they just admired the capacitors, transistors, and resistors on the circuit board.
Mike also used the remnants of a rotisserie chickens to give the kids a hands-on Biology lesson about skin, muscle, bones, and more. Here they are learning about how cartilage helps helps joints (like elbows) move.
I know Mike is really looking forward to the day when the kids are old enough to learn about computer science with Dad =)