How to ignore stupid students/teacher

Thx guys i will contact school concelour i hope its totaly confidential :-) and sorry for spelling/paragraphs i was typing here for first time and when i woke up:-)

Some people said whats the 'reason'behind their behaviour. well dont have any clue as i try to concentrate on work and lecturers i am polite person.other girls said they dont like this two girls as well, and one of these (Brasilian btw) is main iniciator. she is missing lot of classes and work and behaving like celebrity,shes been told twice by different teachers she should change her behaviour.shes talking loudly during lectures -about her bf's, facebook,shopping etc.she and the other girl gets bored very easily, they complain about how bored they are. that could be reason why they r looking for some fun.the same could be with that teacher perhaps who seems to get on with them and their childish conversation.they told him few times to shut up lol. but well its not my business, just needed to write down.