Ditto DeHe on taking a break!

My DH is a "fix the problem" kind of person, and I can see him doing exactly what your DH did. He sees that his method of "helping" with the math didn't work, he feels like he failed, and he needs to find a solution. But sending your DD to middle school as "punishment" doesn't sound like a good plan.

I would try to look for common ground with DH (once you aren't mad anymore) - you both want your daughter to be happy and successful and not have her schooling take up so much emotional energy in the house. Maybe make a list of options?