He needs interesting challenging things for his brain to work on. If he knows all that material already, then he is trying to ... "cope" and amuse himself.

I think other parents will chime in. You're not alone. This is the place to be.

Can he read? (Not all gifted children read early.)
Numeracy?
Written output?
Puzzless? Mazes?
Chess?
Art work?


hang in there