When students submit an assignment in Google Classroom the date and time is recorded in the submission history. Students have the ability to unsubmit assignments. Unsubmissions are also recorded in the Google Classroom submission history. Clicking on a student on the left side of the assignment grading page reveals the students submitted work and private comments. There is also a small link under the students name on the right side panel that says “(See submission history).” Click on the link to reveals the timestamp of each time the student submitted or unsubmitted.