Consider assigning various roles to discussion participants.  For example, if you are studying a topic you may want to assign the roles of the various stakeholders to learners. You may want to first break learners up into smaller discussion groups.  They would then respond to the discussion topics and peer posts from the perspective of their assigned role.  

Another option for assigned roles is to again break learners up into smaller groups.  You may want to have more than one learner assigned to a role.  Create and assign roles such as:

• Question Creator-the learner in charge of composing the discussion topics or questions.
• Replier-the learner who replies to the discussion topics or questions.
• Commenter-the learner who comments on the replies to the discussion topics or questions.
• Related Media Searcher-the learner who searches for media related to the discussion.
• Fact-finder-the learner who finds facts to share about the discussion topics or questions.