One of the  changes made to Google Drive and Docs this summer was the addition of the Suggesting option for edits in Google Docs.  Previously if you wanted to suggest any changes in a shared document, you could add a comment to the side or just use a different colored font to add that change.  The addition of the Suggestions Tool allows you to more easily add those changes while being able to see what it was like previously, and then easily add or delete those changes with the click of a button.

This small improvement could easily improve group work between students or help teachers provide constructive feedback for students as they are writing.  The Suggestions option is in the upper right and you can just click it to go back and forth from Editing to Suggesting.

Watch the video below to see how it works and play around with it before trying it with students.