When to use a discussion forum or a virtual classroom

There is often a moment when an instructional designer is designing a blended-learning program when something comes up that is best dealt with as a conversation between the learners. The next question is, should this be a discussion forum, or should it be part of a virtual classroom? The decision should be made with consideration to the nature of the topic, who the learners are, and the modes that are being used in the blend.

1. The topic
If the topic is a debatable one, then a discussion forum is probably the best fit. These types of debates can lead to highly-reflective conversations. If the topic is complex and new to the learners, then a virtual classroom might be best. A virtual classroom enables the learners to quickly ask questions and explore new ideas.
2. The group
Some learners just don't like talking in groups and there will be a low level of participation in real-time learning events.
3. The modes
If you are not running virtual classrooms as part of the blend, then adding a single virtual classroom, with its potential for technical challenges, the need for a headset, and services being blocked by a firewall, might not be worth the effort.