This is another category of using social media in education. Teachers create groups or profiles in order to communicate with their students and parents,upload relevant material or assign homework. A teacher may use it in his/her own way. It is a very useful tool as the vast majority of students use it and are familiar with it.
Here are some examples of facebook profiles which belong to classes/schools:
In fact I had a problem finding many facebook pages that belong in this category because most of these profiles are private for clear cut reasons. (I will add a post for the reasons why you should keep some points private)