[pepyn]

I teach a programming class with ~50 kids, aged 9-15 and we got started using Scratch [1]. It's not quite coding but teaches a lot of important programming concepts, and is really easy and intuitive for kids to use.

After we played around a bit with the editor we checked out games that others had made, and the kids were super excited when they realized they could actualy build the games they had played themselves.

I'd let him/her play around in Scratch a bit, show some existing projects, and then build a game/project together from their interests (which is roughly what we do in our class).

[1]http://scratch.mit.edu