You could do this with a CS background, I think. Relays are very simple to understand. If current is flowing from A to B, then current can flow from C to D. Otherwise, it can flow from C to E. They way they work (conceptually; I've never taken one apart) is that running current from A to B powers an electromagnet. There's a wire tied to C and the other end is pressed against E by a spring. The electromagnet pulls on the spring and moves the wire from E to D. They're just little mechanical if-then-else constructs.

If you run a wire from B to C and connect a battery to A and E, you'll get a nice buzzing sound as it oscillates between states.