We use Moodle for similar types of learning where we want participants to examine what they know, exchange ideas with others, then re-examine their own initial thoughts in light of the discussions. We work in this way with a wide range of courses and participants, from youth start programs to learning about wine (wih online wine tasting sessions). We've found that it works extremely well to have a scheduled live chat session to start the ball rolling. This means that opinions can be exchanged and questions asked in real time. At the end of the chat (conference), each participant goes away to think things through and to post a message to a discussion forum reserved for that topic. This allows the group to see each contribution and to raise questions or comments afterwards. Rather than a formal grading, participants aid us in evaluating the quality and reinforcing the validity of the contributions. Would this work with your group?