I like this explanation about how to use Google docs for such deep feedback.
How to Use Google Drive for Descriptive Feedback. Act on John Hattie’s research suggesting descriptive feedback has the greatest influence on learning.
He owns a typewriter and collects Laserdiscs. He loves his three children quite a bit (aged 11, 16 and 18). He is passionate about authentic learning, technology with purpose, and creating at least one new thing every day. In short, he teaches, and learns. A lot.