How to arrange 13 class to play basketball!

I suggest adopting the grouping system and dividing Class 13 into 3-4 groups by drawing lots. First, the group points competition will be held, and the first place in the points will advance, and the top two in the group will advance. At this time, pay attention to the multi-class group, because this group is large and the competition is more intense, so the promotion of the top three is carried out in this group.