This came up yesterday at school. I had been up early to prepare a lab for my Form 1 Physical Science class. We are studying methods of separating mixtures. I was just explaining the lab to my class when a school prefect came in. He said he had a list of the students that reported to school on time that day, and that they were the only ones allowed to be in class. I looked at the list. It had about 11 names out of a class of 90. So basically my whole class was supposed to be punished during my lab period? No way was I gonna let that happen.
I told him that my students were not going to leave my class because we had a lab, and that he should let whichever teacher assigned the punishment know that they should be punished afterschool for their tardiness if need be. Then I sent him on his way and I gave my class a quick lecture on how they need to be at school on time because I don't want them missing my classes.
After that we had a great lab. We looked at separating mixtures by evaporation, filtration, chromatography and hand-picking. It was more of a demonstration since we have very few materials, but I was able to have each group come up and observe all the separations and answer questions about them.