The ability to input grades from tests quizzes and exams
There is an app on Google Play named School Planner. You can add grades from tests that you did on a subject. It calculates the average, and you can choose the weight of the tests! My Study Life should do the same thing, and add email notifications in general.
being able to input percentages/points that assignments are worth on each assignment and then input the points you received for that assignment later would be really useful for keeping track of your grade in a class