Open the attached site, but DO NOT EDIT on the original site. Instead, click the "snowman" menu and duplicate the site for yourself. Add your name to the title of your new copy and immediately do these two things:
1. Add me as a collaborator by name
2. Attach the URL from the editable site to this assignment as a link (or attach from Drive directly)
Submit when finished.
Note that this method does require some understanding on the part of your students. If you don't have too many students, you can also make the duplicates yourself and share them individually. Then you own them to begin with and you can keep them all in one folder for follow-up. Students can even submit links to specific pages as assignments in Classroom later on.