Mr. Carter[1] teaches science at Hazelnut Middle School, and he seems to give detention--especially to Pepper Ann --every chance he gets. He also tends to get into his lessons; what other teacher do you know of that begins a lecture on bacteria in food with the statement, "Today's lesson is: Multi-Culture Mass - The Miracle of Yogurt"?
He is voiced by Jim Cummings.[2][3]
Personality
While Mr. Carter seems to be particularly hard on Pepper Ann, he does think she's a good science student, and he gives her credit when credit is due.
Mr. Carter does have a life outside of school. We know nothing about it, however, except for the fact that he dated Pepper Ann's mother for a while. That didn't seem to work out, so he moved on. He seems to be particularly attracted to Ms. Stark, the math teacher, but we don't know where that one's been or where it's going.