Kaizena is a free tool that you can integrate with your Google Drive account to leave voice comments on the the documents that your students share with you. With Kaizena authorized to access your Google Drive account you can highlight portions of your students' work and add voice or text comments to it.
Until this week Kaizena only allowed you to import one Google Document at a time. This week Kaizena announced support for importing entire folders from your Google Drive account. An archiving option was also added this week. The archive feature allows you to remove a document from your account, but the student retains the voice comments.
Applications for Education
Kaizena may not save you time in giving feedback to students. However, for students who need audio support Kaizena could be an excellent way to provide that support while giving them feedback on their written work.