Sakai Discussion Forums
The forum takes a little getting used to. Each forum has settings, and each topic has settings. You configure these settings first before you write a message in the forum. In the settings, it appears best to leave the long description blank because it only shows if the student clicks details.
Concerned that students might not know what to do at first in the forum, I worked to craft a startup message that would have the correct wording both places it appears, i.e., in the topics listing, and on the topic page. Here is how I worded that message:
General Discussion
To participate in this discussion, click the heading of a message to read it. Then you can (1) click Post New Thread to create a new discussion thread, or (2) click a thread's heading and then click Reply to respond to it.
I like how the forum statistics enable you to see each student's level of participation. This is particularly helpful when forum participation is a requirement in the course. You can even grade a message in a forum if you have created an assignment that requires participation in a forum. I like how you can sort the forum statistics by column categories.

