for the people who are wondering why the teacher couldn't protect the boy :
first of all, the boy completely overpowers her by fighting skills and such. While her on the other hand doesn't know how to fight + doesn't know how to stand up for herself. Even if she did tell the girl to stop doing that, she wouldn't listen. The teacher was also injured, the teacher also mentioned 'she couldn't move' probably out of fear. She's a weak human being who forgives people easily.
ANYWAY I DONT RLLY LIKE THE GIRL CAUSE THERES OTHER WAYS TO FIX THE CLASSROOM (i dont remember the guy and girls name)