Ah, well if its the same movie i'm thinking of then the movie is called "Only The Strong"One of my favorite movies. Mark Dacascos plays the teachers and instructor. The program he teaches is actually like a gym class. He takes the 12 worse students out of the school and teaches them, but one of his students is the cousin to the leader of a major gang. They cross paths at some point and thats where the school is set on fire and the student dies..
Hope this helps..