Once you get your sim to an A, you don't have to do the extra credit homework. You don't have to do extra credit beforehand either, all it does is speed up the process of getting to an A. And as I said earlier, once you get your sim to an A, you can get away with skipping homework every once in a while. In fact, if your teen has vacation time accumulated and you don't plan to send the family to Granite Falls, you can have your teen take 3 or 4 vacation days, which might be enough to get him to YA.