If all teams picked red, they all scored -4. OK, you get the idea. We all understood the point immediately. As long as everybody went with green, everybody scored positive points. If everybody picked red, everybody went down together.
Competition is bad, cooperation good.
We wrote our colors on pieces of paper and the teacher picked them all up before reading them off. We all chose red. All four teams stood at -4. OK, the teacher says, to give us a chance to get caught up, for the second round, he'd triple all the scores. My team talked it over.