Well, no, there's no reason why a student account currently being used as a student account would need invite codes, but if they roll it from a student account to a standard account after their class, they will be receiving invite codes at distribution time and the kid can do what they like with those invite codes.

That's not the teacher's doing, of course -- but the point is, there's a real limit to what you can do to prevent a parent freaking out at a teacher if a kid is smart enough to get access to porn via DW but not smart enough to keep their parentals from finding out. *shrug*