Groups is a very basic feature in Moodle, and it will also help with our very large numbers.

We can auto-create some groups of size 5 people or so and apply them to a forum in second week or so.

Activity could be for everybody to take the role of a teacher and to start one discussion where they try to teach everybody else in the group about a topic that they know about.

This gives them the experience to experience groups properly as a teacher and a student.