Hi Melina,
Another plugin possibility is, Hot Question. It can be set up to allow users to post anonymously, or use their name, when posting a question. It supports voting on a question so if someone has already posted a question that another user would also like to ask, they can just upvote the question without having to write it again. Hot Question also supports adding comments to questions, so teachers or anyone, can reply/answer directly on each individual question. If posts are not anonymous, the activity can generate automatic ratings based on participation.