KJP, you've received wonderful advice already, but there's just one thing I'd add. Are you sure the issue is the age range of the kids, or is it possibly the setting he's in when the challenges arise? I'm just curious because the place you've mentioned having issues is in the classroom, and the places you've mentioned with other-age kids/etc are activities etc outside of the classroom. There may be different sets of expectations/etc that he's responding to differently in the different types of settings. So that's the one thing I'd want to think through a bit more, and I would think through it now, while you're familiar with the setting of his classroom etc. Leaving it until next year might mean everything magically is better - or everything is the same, or (hopefully not) everything is even more difficult at school - it all depends on what's really going on. So I'd try to figure out what you can now.
Best wishes,
polarbear
