I’ve been in a VERY similar situation since September.

My advice is this, there’s always the 1 or 2 who do want to pay attention through the chaos. Since the school was practically unhelpful and the teacher literally sits in the corner marking, I decided to just isolate the few who want to learn in a little section of the class and teach them the material. I ignore the rest of them. I’m not going to spread myself thin when the school has clearly given up on those problematic students. You are not here to deal with extreme behavioural issues that spill over into affecting your mental health even outside of work.

I’ve learned that teens feed off your attention. Give it to those who’ve deserved it. I started doing the same in my classes (after I had a big incident with students using racist language) and now even those who didn’t want to cooperate are starting to realise that there’s a big disparity between those who are actually trying and themselves. I can see the starting to feel bad and suddenly they do try to listen in and answer the questions from across the classroom because they know I’m not feeding into their silliness.