Like others have said, every school is different, and every school has their own board to set their standards. I went to a public high school where you had to have a 96% or above for an A, and eligibility was decided by semesters. So if you were ineligible at the end of May you didn't play sports until after Christmas the next school year. At the time I hated it, because others had it much easier. But when I got to college. I felt I had it easier, because I had already been pushed to work harder to make it.

Just my 2 cents for what its worth.