How far should a teacher investigate?

[harwarda]

Sara B is right. This teacher has a responsibility to investigate. You may not be bothered by what people are posting, but there have been cases of students who were bothered enough to commit suicide. This isn't about you- it's about the bullies. If they are not caught now, they may do something worse to someone else.
What do you mean "only the music teacher"? He's just as important and responsible as any other teacher. In terms of what you should be learning to have a good future, music might be just as important as your other courses. Just ask the contestants on The Voice UK (although I am shocked at Ruth Brown being voted off!)