Can he do a pre-test and if he gets 85% or higher (he should not need to get 100%) can he opt out of most of the classwork and all the homework for that unit? Clearly, he may need compacted instruction if there is something he doesn't quite understand, but it probably won't take much for him to learn it.
Doing the regular classwork and additional worksheets may start to really bother him soon.
I would see if they would do that AOPS in school if he is enjoying it.
You may need to bring in some supporting evidence about differentiation in the classroom (different work, not more work).
Honestly, if I had the chance to go back again, I might have been a real pill of a parent and just told them my kid was not going to do homework at that age. I don't think there would be anything they could have done about it. Doing homework on things way below your level can be maddening. It seems like the "right" thing to do to be upset with your child's attitude, but I disagree. He could have a really great attitude about doing work at his level.
Good luck with your meeting!
