I haven't read through the other responses yet, but I just wanted to share a quick thought:
What if you both start the school day with a fake tantrum - a litany of "Boring, boring, boring! I can't, I can't, I can't!" Make it funny, get him laughing, tell him you want to get all of that out first thing so you both can get down to the business of learning. Then, when he starts up, tell him, "sorry, we already covered that for today. You'll have to wait until tomorrow morning to do any more of that."
I haven't a clue if that would work, of course, but there's a chance he will come to see it as an obstacle he puts in his own path.
OK, back to the top now to read what the smart people had to say.
