Tracking and evaluating student work in Google Docs using the share features can be a bit daunting if you are not meticulous about your organization of folders.
Another option is to have students submit their Google Docs in Moodle as an "Online Text" assignment by pasting the URL link from the Google Doc (note: this only works if the link is copied from the Share link feature under the share tab)
This tutorial walks through the steps of adding an "Online Text" assignment submission link and demonstrates how students would share their Google Doc link to your Moodle course.
