Those who say that the teacher handled it wrong are correct, but I will say this:
It's a very tough job and they definitely don't make enough to have to put it up with all of the disrespect. They are often doing a parent's job (some kids don't have parents, and others have parents that are too busy with work to properly raise them).
I remember one of my favorite teachers left the city high school to go work at an Upstate Private school the first chance that he got. Yea, the salary was probably better, but I'm sure the general attitudes of the students played into his decision as well.