Has the daughter’s feelings been addressed by the mother with the school? Even if she has nothing concrete to point to, I would think any nest of libs as deep as a public school would bend over backwards to accommodate a female student.
Alternately, have someone go with her to the “individual instruction”. Schools like that often have counselors and “mentors” of all kinds (gotta do something with that sociology degree), so they have all kinds of useless staff around to “assist” students. The only thing to be careful of there is that the art teacher may be well-liked enough by the faculty/staff that the school would back the teacher over a student if something were to occur.
Her mom will talk to the school again tomorrow, so far they’ve just been told she can’t drop the course and if she doesn’t show up will receive Zero’s on her report card for the next three quarters and final exam.