Do threaded discussions work?

I'm talking about classroom forums like Nicenet and Blackboard. I am also thinking about any of the millions of topics-based forums that exist. Online forums are a major part of what Will Richardson refers to as the Read/Write web. When we are using online forums, we are reading what other people have to say and contributing in kind. We respond to others' opinions and other people respond to our opinions. We tend to carry on several asynchronous conversations simultaneously.

While it is true that there is a certain amount of talking to hear ourselves talk, for the most part, real communication is going on. Ideas are evolving through their interplay with contesting and complementary ideas.

This works extremely well in topic-oriented forums where everyone who participates is doing so by her own free will and because she is interested (sometimes obsessively so) in the topic of discussion. However, threaded discussion can become a pointless exercise in a classroom setting IF students don't have a good reason for doing it.

I learned this the hard way in my 4790 class I taught last semester. I had expected the online discussion to be one of my students' favorite tasks, but a midterm survey I conducted showed the opposite to be true. Almost unanimously, my students said the online discussion was redundant with the classroom discussion we were already having. From my subsequent conversations with these students, I've put together the following guidelines for a successful threaded class discussion:

1. For threaded discussion to be useful, students need to respond to each other. If they are each posting without reading each other's posts, then we just have a writing exercise. As I said earlier, it is the interplay of ideas that causes ideas to evolve.
2. Threaded discussions must be seen as a path towards a destination, not the destination itself. Threaded discussions should be the kernels of future papers and projects.
3. Topics can arise naturally from class discussions, but should never merely repeat class discussions. It's more useful for a topic to preview an upcoming classroom discussion.
4. I like to think of threaded discussions as thinking out loud. Students should feel safe to play their thoughts out in their infancy in this very public forum without fear of ridicule.
5. Expectations should be explicitly stated. Unfortunately, it might be necessary to require a minimum word count, a minimum number of posts (weekly or semester), or minimum number of responses to other students' posts. I recommend weekly deadlines for posts.
6. The instructor should take part in the conversation, but only to model, not to instruct.

Although blogging is different from (more sophistated than? more adaptable than?) traditional threaded discussions, the same rules should apply when using them in an educational setting.