How to deal with Teachers!!?

Ok so my teacher not only compared me to other students in the class while they were all listening and she said it in a loud voice but also, on a test, me and my friend spelt this word the same and she marked mine as wrong and my friends as right!! I went up to her and showed her and she was like "Oh" and didn't even say sorry and when she said oh it was like a mean sorta tone. This teacher was nice but why is she being so mean to me?? When I tell my friends they all say she doesn't like me that it seems that way. But why? I listen to her as best I can, I do everything she says without question and everything, I really try my best! Mind you she is my full on teacher-primary school. so I can't just move on 40 mins later cos I have her for the whole day! Any help????? I haven't done anything to her and she was nice to me but all of a sudden its as if shes on dark side and im on blue side!!