What am I going to do?

Hi, in my year in year nine we are split into five groups and I am in the middle cl. Our cl is really and misbehaves. Usually I stay out of the trobule but for the past two weeks I have got in trouble for either being late to cl or talkingbut nothing serious just a quick "stop talking please." Recently, I got into trouble for something I didnt but then i later found out I did do. Then not going to a detention I knew nothing about so I have a longer detentions. It seems as if a few of the teachers dislike me. How do you know if the teacher doesnt like you or has been talking about you in the staff room? After our SATS exams we are going to do our core subjects together (Maths, science, english) if you get good you go into a higher test paper set and if you get bad you go into a lower set. Last year this girl got moved into a higher cl, she wasnt exceptionally clever. She was really well behaved though. Never EVER talked back, got rude, came late except she had a note