Because Schoology is built on Google’s permission-sharing capabilities, at this time, all student copies are only shared with the user who created the assignment and the student who opens it. All other visitors to the course, whether co-teachers, admins, advisors, will not be able to see the submission.

The student *may* be able to share the doc with you on the Google Drive end of things
That would be working around the permissions. The co-teacher may be able to as well.