All grades are plotted along the normal bell curve. Department Of Psychology Students are asked to blot ink in their exam books, close them and turn them in. The professor opens the books and assigns the first grade that comes to mind.
All students get the same grade they got last year.
Department Of Physics Grades are relative. All theoretical chemistry is really physics. All theoretical biology is really chemistry. The history of all hitherto existing society is the history of class struggles. YOUR grade is an object in a class of its own.