If the pairings of courses and students are registered in the school object, then that's basically OO implementation of a many to many relationship of students

If the pairings of courses and students are registered in the school object, then that's basically OO implementation of a many to many relationship of students and courses. That's why I like Django. You just tell it that you want a many-to-many between students and courses and it does they for you, symmetrically, without forcing you to introduce a class such as "school".