Really Mean And Scary Teacher?

She could have just been having a bad day or is just generally mean. She didn't mean anything by the comment its not like she's literally going to rip you apart. That is technically a threat and you could report it to the principal but chances are unless other students have had the same problem with her then nothing will happen. If your worried about it then you should go in to the principal and tell him/her that your generally a good student and your scared or worried about what she said. Hope this helped