Provide explicit guidelines in your syllabus for your expectations about online discussions and your reasons for using them.Make online discussions integral to the course activities and assignments. Avoid having online discussions become what students may view as "busy work."
To begin an online discussion, provide specific, clear writing prompts and questions related to readings, course activities, or course goals. Often, the key to a good discussion is a good question. Refer to Bloom's Taxonomy or other models for effective questioning as a guide to develop questions that encourage comprehension, application, analysis, and evaluation.
Participate in the online discussions yourself as a teacher. While you should not be expected to respond to every student's post, faciliatating a discussion is not a spectator sport. Even brief participation in the discussions will help you familiarize yourself with your students' ideas, perspectives, questions, confusions, and insights. Model critical thinking for students. Affirm student participation with your attention and interaction.
For large lecture courses, spot check discussions and/or have TA's spot check with you.
Draw positive attention (affirmation) to a thought-provoking post or a thoughtful reply during the online discussion and as a follow-up in class.
Make general observations about the nature of postings that are not particularly well-thought out or that lead the discussion nowhere.
Encourage students to provide brief specific subject lines describing the main emphasis of their posts.
To generate interaction, (a) ask students to post a response and then respond to at least two other students' postings; (b) ask students to post a question of their own at the end of their post; (c) let students know that at the end of the online discussion, you will randomy call on several students to summarize the main points or differing views that emerged during the discussion.
Establish criteria and rubrics for evaluating students' content, expression, and/or participation in online discussions. Before faciliting online discussions, determine your objectives and what aspect of discussion/interaction you want to encourage and promote. Make the criteria explicit for students. You may even ask them to formulate criteria with you.