Once you've assigned a quiz, you can see who has completed the assignment by navigating to your class.
1. Click on My Classes and then select the class you assigned the quiz to.
There, you will see an overview of all your assignments. You'll have a snapshot of how many students have completed each quiz.
2. If you click on a specific assignment, you can see which students have completed it, and which still need to do it. You can sort by Date Completed to see students who have and have not completed the quiz. (If they haven't done it yet, they'll have a -- instead of a date.)