CS Unplugged: Computer Science without a computer and Nine Algorithms That Changed the Future: The Ingenious Ideas That Drive Today's Computers. I've also posed a problem for him to ponder:
"You have five fingers on your hand (usually -- a few people have more, many have fewer). Each finger can be either extended, or curled up. So a fist would be all fingers curled up, a high-five would be all fingers extended, and many other combinations exist (including the obscene middle-finger gesture, and probably a whole lot of gang signs). What is the total number of possible combinations that can be produced using five fingers? Can you do them all? What is the total number of possible combinations that can be produced using ten fingers? Can you figure out a pattern so that you could calculate how many possible combinations there would be if you had 16 fingers?"