It also comes down to what you see as the role of the school system. You get into a dilemma when you have a kid who does so badly in the beginning he pretty much has no chance of catching up later on. On the one hand, you could tell him, "sorry kid, you blew it", and he will likely neglect the rest of the class as he has no chance of passing it anyway. Or you could say, "you have done horribly so far, but if you put in a lot of effort and show great improvement during the rest of the class, I might still pass you", and he will be more likely to at least try. The first approach is more fair if you simply see school as a way to assess students' abilities (though it doesn't account for late bloomers, students going through hard times, badly designed tests with respect to score variance, etc.). The latter approach might be better for optimizing learning across the board.

/Ulf