Student Group Calendar that is not full

Hi, is there any way to see student group that is not full?

For a private lessons company that each student should choose their own schedule.
So administrator can tell student which schedule is available for student to choose.

There is 2 schedule for math class for every weekday. 8.00 and 10.00. Therefore there are 10 schedule every week.
each schedule should only have max 3 student each.

How can I get which class that is not full?
Bonus if it can be shown in calendar view.