CheckMark is a brand new an extension that was developed to help make it easier for teachers to provide feedback to students in Google Docs. Once you add the extension, all you do is highlight where there is an issue and select one of the nearly three dozen canned comments. These comments include the most common mistakes such as capitalization, tense, rephrase, and subject/verb agreement. 

Applications for Education
This extension will save teachers lots of time. Students could also use this extension to provide feedback to their peers or teachers could provide students with a Doc that has mistakes in it and have students use this extension to locate all of the mistakes.

Click here to see a demo of how CheckMark works.