How do i get a girl twice my size to back of?

i would just keep doing what you are doing. just ignore it and don't react to it. eventually it will get old and she will move on. if it doesn't stop i would go to the principal or maybe the guidance counselor to try to resolve the issue with her. you should feel safe at school and anyone that is making you feel otherwise should be confronted by a person of authority. please just don't say anything back it will just make the situation worse for you.