I'd suggest picking something relevant to the things he's already interested in like modding video games. Obviously this is personal to us all but I learn best

I'd suggest picking something relevant to the things he's already interested in like modding video games. Obviously this is personal to us all but I learn best building things, and I'm most likely to stick to building things I'm interested in. SICP is great for those who want to learn more about programming after they have some experience programming. If someone gave me that book as my first one I think I'd have picked a different career field, even though I am now - 8 years later - working through it :)