This full pdf text is quite good. I taught a second year series micro course using an older edition of this text. Your son will be able to skim through much of the material. Most first and second year university micro is accessible to a bright high school audience and can be taught without calculus. I'm confident you son will be able to manage this material.

http://lms.unhas.ac.id/claroline/ba...TAucGRm&cidReset=true&cidReq=136A113_004

What is to give light must endure burning.