Another option for sharing just one page of multiple page Google Doc would be to export as a PDF only one page of the Google Doc then share that one page PDF in Google Classroom. Students will then have to use the “open with Google Docs” option to convert the PDF back into a Google Doc that they can comment on or edit. The process sounds complicated, but it really isn’t. In the following video I demonstrate that process from a teacher’s perspective and show it from a student’s perspective.
Applications for Education
Why would you do this? I've done it with lab procedure documents from Cisco NetAcad that I have as PDFs when I want students to do the first part of a lab but not the second part on a given day. By sharing only the first page I can be sure that they won't go ahead to the second part of the lab without me supervising it (particularly important when working with electricity).