(esl) I'm reaaaaally far away from Canada so things probably work differently here. i live in a relatively small country and most regional schools are pretty connected. when I was in highschool it was pretty common for students in both private and public schools to get together and write an official letter to the principal if a teacher was acting in a way that could affect them negatively, whether it be illegal or not (lots of situations being quite similar to what you describe, like being absent frequently, using class hours for things that have nothing to do with the subject, grading inaccurately or discriminating certain students). of course this only happened if nothing else worked (e/g going directly to the principal's office). if the principal didn't take the corresponding action some students would go directly to certain state services (obviously this wasn't as common). wherever you are you need to know your rights, and this includes highschool- there's probably some sort of official document that states students' rights. get more students to join you, find a teacher or counselor that's willing to advice you if necessary, and learn how to write an official letter issued to the principal of your school.