Have you talked with the head director (do this first) or school leadership?

Coaches have film on Saturdays, so—unfortunately—it can sort of be justified.

I was one of two assistants who had to teach lessons until 9:00 PM each night, plus 10:00 AM to 1:00 PM on Saturdays (in a small West Texas town 25 years ago). 80% of the students never showed up, and the head director was nowhere to be seen. After one year, we moved on. You can try to draw a line and say no, but you will most likely have to move on as well. When you become a head director, remember the balance needed—and don’t pull crap like this on your assistants.

— Dies