How's this structure?

[Banaticus]

StudentInfo
-----
StudentNum
StudentName
etc.

InstructorInfo
-----
InstructorNum
InstructorName
etc.

ClassInfo
-----
StudentNum (related from StudentInfo)
Name
Grade
StartDate
EndDate

Classes
-----
InstructorNum (related from InstructorInfo)
Name
StartDate
EndDate

Classes will have rather tempory data. After one class ends, the users want to be able to delete it and recreate it. Or, simply change the start/end date/time. So, I plan on making it possible to do that, but I still need to save which students have taken which class and be able to easily add new students to a class and be able to store their grades and such.

So, I thought I'd start with a form something like this -- what do you all think about this? I put in a list box in the bottom left corner (Classes list), so that I can more easily run events off that box -- so that when a user selects (clicks) a class, the subform on the right will be changed to show students in the class. As a subform, the box on the right will enable students to be added to a "class" and the information will be stored correctly in the tables. At least, that's my thought, although I'm not quite sure that this is really want I want to do. It seems like a lot of duplication of information, although (as stated) Classes will be deleted on a regular basis and I need some way to match up Classes with Students who are in those classes then some way to store the Grade, etc., that the student had in those classes.

Almost forgot. I'll be putting in a button by the listbox in the bottom left corner so that a user can add a class to the list or delete a class from the list.