What you did, I have no problem with. But, you didn't really expect to change this ignorant guy's dumbass opinion did you? You sound smart. Smart enough to know that you weren't going to change this guy's teaching method in the slightest even if you shot him in the leg. So, in it's real essense, the arguement was totally useless, and did nothing but hurt your grade. Next time, don't waste your time.

I learned something by being mildly intelligent and going to 'bad kid/stupid kid' school. Don't ever correct a teacher. All it'll do is piss them off and thereby get you a shitty grade. And they can almost always come up with an excuse for giving it to you.