If my daughter was a victim of a sexual assault in a classroom by three classmates and the teacher was present can she be sued This happened in the state of Texas?

First off, apologies all around to your daughter being assaulted. Very horrific experience, and I hope you're getting her help.

To answer your question: If the teacher was present, was aware of the assault, and didn't do a thing to stop it, she (the teacher) can be sued. However, if she (the teacher) was also being attacked (either physically, sexually, or otherwise) at the same time, or was being restrained from stopping the attack, the courts may say her liability is limited.