Exercise Group Allocation
Why am I in an exercise I didn't want to be in?
The fact that students did not end up in the groups they wanted could be related to the fact that too many students registered for the most popular groups. If too many students sign up for a group, everyone who no longer fits into the group will have to be reassigned.
It could also be that you have indicated “no preference” for this exercise. This means that you do not care if you get this group or not.