What sort of dialog are you able have with your son? Can you discuss how this looks to other people?

We've gone through that with my DS8. Some of the things we've explained have been:
- People will view such things as bragging, and won't even remember what you actually know.
- In a classroom, the teacher will know you know the easy stuff, only offer answers for hard questions.
- Conversations are a series of permission passings, dumping a bunch of information without request can be considered rude.

Usuallly I'll get to the point by asking him what he thought action xxx would do? Then get into how it won't succeed or it would have secondary effects. And trying to make each solution his own (Socratically led) conclusions has been helpful with my Mr. Know-It-All.