Tutors choose a student at the end of a session to be the "scholar" of the session. Every time they receive the "scholar" title, they will get one point. After x number of points have been acquired, they can spin a wheel to win a prize. This will give learners the initiative to pay attention and engage in class, join sessions with less people (as it gives them more of a chance to receive this) and it prevents spam joining classes. -Raina's suggestion
We could also only let the learners know that they can spin a prize once they reach the number x/don't tell them who became the "scholar", as I think that if they find out that they were not selected, they will give the tutor a bad rating, or not attend another of that tutor's sessions. -Athena's addition