You enter your subjects, enter your types of grades (like, for when Homework = 20%, Quizzes = 30%, Tests = 50%), and then enter grades when you get your papers back from your teacher. It'll do your average! You can do grades based on percentages, such as a 93%, or as parts of a smaller whole, such as 15/20, and it'll all come out right. It saves you the irritation of constantly asking your teacher to look up your grade, as well as giving you the ability to play with your grade and see what you have to make on a test to pass for the current grading period or anything like that.

The only bad thing I have to say is that you can't re-order the assignments once you've put them in. Seeing how trivial a matter that is, the app is great overall.