This is actually a very interesting feature and can be done with a lot of flexibility. Here's one way it could be done:
create a group for a class
add the central questions of the course to the group. This can be done by the teacher or as an assignment by students. As a student assignment in a small class, a student could add a question every week that encompasses the main theme of the topic of the week.
as the moderator, the teacher can then oblige all students to answer a number of questions as well as highlight comments that best answer the question.
the information can then be stored and be used for revision.
for a course that is taught every year, new students can be added to past groups. This can be helpful in seeing a progression in opinion and knowledge on the same questions still being discussed.