They just think their teachers are fucking assholes. For the sake of argument, let's work with the premise given. Kids are predisposed to hating their teachers, so it's pointless to make the teachers likable until the aliens take them over. Then, after the aliens are gone, they are likable again. For a movie the kids will love, make the teachers mad as hell at the kids for not following their rules.
All kids hate the fucking rules.
Make the teachers resort to brainwashing and killing the teens to get the school in line. Make it revolve around an accreditation visit by the state, and this is why the teachers have to remove the rotten apples. He could have probably gotten Hey Kids, get Filthy's Reading , Listening and Movie Picks for this week. Now, however, he's a lot like the new kid at school that seemed cool until everyone found out he was autistic and could only do one thing. You're a broken record, Kevin, and you're schtick is wearing out.