Draftback lets you play back the revision history of any Google Doc you can edit. It's like going back in time to look over your own shoulder as you write.
Notes: - With Draftback, your data is kept entirely private. Draftback was purposely designed so that you could play back your own docs without having to share them with a third party. This is -your- data; Draftback just lets you see it in a new way.
- Draftback only needs access to docs.google.com to get the revision data for playback—but that data never leaves your own browser.
- New!: It's now possible to extract any part of a doc's playback and embed it on the web. (This, of course, makes that extract accessible to the public.)
When used in conjunction with Google Classroom it would enable you to see a student work on a document and their writing process. When used in group projects you would be able to see how much each students contributed to the document.
Below is a video detailing how to use Draftback with student writing.