Ask HN: Resources for Mentoring a Coder?

A friend of mine asked me to mentor him. He started coding PHP several years ago and is now doing Ruby-on-Rails. He loves coding (like most of us) but doesn't have the foundational knowledge of algorithms, data-structures, and computer architecture.

I'd like to help him get started on that foundation in a way that's fun. Originally I thought we'd go through SICP together - the book and lectures are both freely available and the fact that it came out of the freshman lecture series at MIT make me think it might be a good place to start. On the other hand, it seems like it might be a little too much for the time we'll have (roughly an hour a week together and whatever time we spend working through it on our own). The "Little Schemer" seemed like it might be a good alternative, but I haven't read it so I don't know.

I'd love to hear recommendations for engaging books that introduce some of the more foundational CS topics while not straying too far from the actual writing of code. Or, if you think some other format would be more beneficial, please let me know. An alternative idea I had was to give a coding problem (for example, "Sort this list") and then work on refining it together while examining the runtime attributes.

Thanks!