For a responsible and correct way to have a classroom discussion, people must keep their voices to a minimum and only talk to the members you're assigned or sitting close with from a certain distance. The reason these rules are important is that the professor/teacher doesn't want the attendees of the class to be distracted with discussions not related to the topic that the teacher has assigned. people won't be able to focus and will have trouble with the assignment, and if they go to others for help they will not know either because they were distracted as well.
