[phobosanomaly]

Have you tried sitting him down in front of Khan Academy on the evenings and weekends? Does he stick with it for weeks and months at a time with little supervision?

Maybe try that and see how far he can go before he gets bored or starts losing interest. If he genuinely blows the doors off of everyone and spends his nights and weekends doing math and he's good in the other subjects, the school would probably be fine with just bumping him up a grade.

Or, if he finishes everything way before the other kids, just start sending him to school with problems out of Morris Kline's Calc book or something, and he can work on them while the other kids are catching up.

It's possible he'll slow down, maintain his pace as he progresses through school, or he'll figure out that he has a burning passion for theater or oil painting or the 300-meter-dash or something.