Excellent that you're having a good experience at school! It sounds like an excellent school. We're in a bit of the same boat, at a wonderful school with amazing teachers, super fast curriculum, and my ODS is very happy. He's beyond the curriculum but enjoying it.
Have you talked to the teacher at all? Seen how he's fitting in at the moment? My ODS was getting very easy books sent home, so we had a chat and she's sending harder books and willing to let him move up as fast as he wants.
FWIW, ODS gets advanced math work outside school, and his reading level isn't limited by classmates. In school he's learning writing (something he needs help with!), story-telling, and spelling, so there is challenge there. But math is really simple (counting to 20, shapes) so it's good to have an out-of-school option he likes.
