I understand the first part, but I don't understand the second one. It's probably my ignorance for not having children and being out of touch with schooling. When I was in school very little grading was based on homework, mostly was grading by testing in class. For example math, I'm absolutely sure it was 100% a few grading tests every semester. You could cheat by copying the homework of your classmates, it was the same set of problems for, but with 0 understanding, you would not pass.