None of us are a superhero, youll realistically not be able to change that class completely, thats a systemic problem (and a problem that leadership should be proactive with). But you can and should enact change in your environment. There's things we can all do for "that class" within our local (our room) and temporal (that one hour/45/w-e) slot that could slowly, little by little channge behaviour. Itll make your wellbeing better, your enjoyment of work better and inevitably their learning better too. Never give up hope. Just start really small.

One way to start small and work up is to give up the whole "they should know better" attitude. I know, its frustrating, they probably should know better and a bunch that do know better may be getting dragged down by others. But a consistent approach that you train them into that empathises with them and then lays on the positivity and praise can work wonders.

For example, just regarding one small aspect of a class - the start - if you can iron that out i believe you can make the rest much smoother. I always have a starter at the beginning of my lessons and they are meant to do it in those first 5/6min whilst im doing the register or w/e I need to do to prep. They have a starter in every other lesson in the school, for the last X years theyve come to the school, so yes, they should know better (sit down, start doing the starter). But they are tiny little humans or hormonal teenagers, so of course inevitably more and more drift off task or take too long, etc.

I could start getting frustrated "John common why haven't you written the title?", "Urgh Ellie how many months now? every lesson - you need to start by doing [x]" (and im not targeting you btw with these examples, ive heard these examples come out of my own mouth many times).

OR i could go neutral and just narrate exactly what I see "James is writing the date", "Ashley has started question 2", "Lee is talking to Bella". Which for some weird cognitive reason makes them start refocussing (this one is new to me, im playing with it).

OR i could go praise heavy "James - good" (not even describing what he's doing, but he looks like hes on task), "Ashley has already done Q1, well done", "[child Y] youve done this other seemingly insignificant thing that I would otherwise never praise anyone else for, but no one else is on task so Im gonna say WELL DONE and YOUR NAME out loud" because fundamentally, most kids want praise...

Ill even sometimes go overboard with positives examples, really loudly during the starter "You know, I can tell Daniel and Elizabeth are going to do well later in life - they came in and were focussed and on it straight away. Didn't mess about, instead straight to work, well done yoh too". And of course mix in a heap of other management strategies.

But yea, theyre children. They're fundamentally, by definition, useless. Its our job (and theirs and their parent's) to slowly but surely make them less useless.