I hate this

Today, we couldn't do anything in my 2nd hour (fitness training) because it was stormy out, and there was a blood drive. Our teacher said that we were going to run a mile Wednesday, and he gave us a simple assignment to do today. I got it done within the first 15 minutes of class, and he said that once we were done we could mess around responsibly. I got on my Chromebook & started writing a short story. Towards the end of class, he comes around and picks up people's papers, and we all hand our stuff in, he looks at people's papers, and he said that THREE people didn't do anything, so we are going to do more cardio (this is very bad for me bc I have asthma). I got upset at this, because he could just punish those people, and not the people who did their work. He knows who the people are, why can't he punish them and not the whole class. Also, according to the Geneva Convention, collective punishment is a war crime, under both international & non-international conflicts.