rude or rasict?

So I'm a new student at a new high school. I come from a town with only 1 school and the school only has 400 kids, all of them but a handful are white. My new school has almost 2,000 kids of multiple races. One day a teacher walked into class and there was a kid who wasn't in the correct seat. The teacher started screaming at him and screaming at him and just wouldn't let go. The kid was black, (sorry if this offends anyone, I don't know how else to put it,) and the teacher got to the point where he was calling him nappy head. When he started repeatedly calling him nappy head the kid finally stood up, said "I'm going through enough at home, I don't need it here too," and left. NO ONE stood up for him. When he left the classroom half ass in tears people were like idk why he's acting like a baby the teacher was only joking blah blah blah. I was wondering if that was used in a derogatory way and is to be considered racist, or just plain rude. What does it sound like to you guys?