apm, those are excellent questions, I had not really thought of those differences in acceleration opportunities! One of the schools I look at provide abilities grouping, mixed age instruction. So you might be chronologically grade 1, but sits with grade 6 kids in algebra, and they do it in the same classroom. But I suppose at some point you might hit a ceiling anyway if you are at grade 8 (the top grade at the school) and need to accelerate several years ahead. The other school move the kids around to the classrooms of older kids, but potentially only up to two grade levels.

I don't know yet whether he'll need acceleration, or how much, since we haven't done academics with him yet.