Round Robin Worksheets

The leader makes worksheet stations around the room and at each station is a worksheet of a certain difficulty.  The leader could use worksheets from previous sessions (if there are a lot of new participants) or could make new worksheets.  The participants self-select the station that they want to go to first (based on their confidence in their ability to work on that material).  They can switch stations whenever they want and the leader will circulate to the different stations.

What happens is:

The worksheets build conceptually, so the participants learn as they go and become able to do more through their completion of the successive worksheets. The participants will work with the other participants at their station rather than wait for the leader to come over (so it forces them to work together). No matter the skill level, there is something active for the participant to do. This takes a lot of upfront planning for the leader, but once they are in the session, they do very little - they just manage the 3-ring circus

This isn't appropriate for EVERY session, but it works well, especially when an exam is coming and the inevitable influx of new participants comes.  Have a couple of new worksheets ready for the regulars, and bring copies of old worksheets for the new participants!  Try it!!!