I think the problem is the way he assigned it. Look at the attached screenshot.
There are 3 choices was assigning:
- Students can view file
- Students can edit file
- Make a copy for each student
If he wants each student to get his/her own copy, he must choose #3.
If he is choosing #2, every student is being given editing rights.
If he chooses #1, every student can view the file, but will NOT be given his/her own copy.
There is no need to have students make their own copies. Choice #3 above will make an individual copy for each
student, and put his/her name on his/her copy. That's one of the nice features of Google Classroom.