[@SepticGentleman] It's based mostly on academics but there are other factors that contribute. Grades are given based on progress within your own timeline rather than on a standardized grade point scale. So more advanced students are pushed to become even more advanced at a steady rate rather than being left out because they already meet a general standard. If you arrive and know next to nothing as most humans do when they're brought in then its not held against you. Classes are held that go over different species' cultures and histories of belief systems and many others. There are also mathematics classes and things of that nature.