Usually when a friend, brother or sister does something wrong, you always rush to tell your parents or an adult first. Sometimes it’s for the right reasons while others, you may want to come off as a better person.
If you are having issues with your teachers try talking to them one on one. It will show them you have guts and they will respect you. If that doesn’t work go to an adult above them or equal to them, either your parents or the headmaster.