Whose side are you on? [assignment edition - mod edit]

It seems obvious to me that the teacher screwed this up and not the student. What the teacher should have done is simply say the student didn't need to submit anything since the last assignment was pointless.

The student went through all of the proper steps to ensure he didn't do what he didn't need to do. The teacher should say something like if you score an A average on 4 exams, the 5th is optional. If you don't have an A average, the 5th becomes mandatory.

There's absolutely nothing wrong with what the student did. I probably would have done the same thing.