Racism at my daughter school - feeling helpless

My daughter is 11. Last week she came home crying because classmates called her names because of her skin color. When I went to the school the principal said kids will be kids and dismissed my concerns. I am furious and heartbroken. My little girl asked me why people hate her and I did not know what to say. I want to escalate this but I am worried about making things worse for her. She has to see these kids every day. How do I protect my child while also fighting for change? Any parents who have dealt with racism in schools please share your experience.