I work in UK Higher Education where its rare for courses to make use of learning technologies not to design in some discussion based learning activities. A common technique for those involved in helping educators design such activities is to use representations of practice. This could include case studies, or pedagogical templates. Quite often, learning technologies come up with their own and I am no different. I try to use representations which have pedagogical rigour but are also easily digestable. The level of abstraction needs to be somewhere between being too abstract for easy application and too specific to be adaptable. Also, a consideration for easy digestion is the length of the representation. Basically, its not good to be too long.
Below are a set of representations that can be used for any online discussion tool. Each box represents example wording that can be adapted for use within any learning activity using this tool. You will notice that there is lots of process support in each wording. This covers how the learners should engage with the activity and explaining how the tutor/facilitator will engage. Such process support is a vital part of the design of online learning activities and often overlooked.
Ideally I use these activity wordings as part of learning design consultation. It helps educators new to e-learning visualise how such activities could work. It also highlight the different types of discussion you can have. I've grouped the wordings within a scaffolded learning process - it happens to be Salmon one but I could have used others. The point of this is to show how discussions can be used at different stages of a scaffolded learning process. What's interesting is that other tools like wikis are more suitable for later stages in the learning process whereas the discussion tool is a versatile and can be used within lots of different contexts.
I hope you find these useful.