In each student's row, you'll see the status of their assignments. Hover over the status and a tooltip will pop up with more information. To turn off tooltips, uncheck the box at the top left of the gradebook.
There are four possibilities for assignment status:
Lab not run
A dash in the gradebook means the student never opened the lab or started the assessment.
There are two types of pending status:
Assessment not submitted
The student has started the lab, but hasn’t submitted the assignment yet.
You've allowed the student to redo the lab and are waiting for a new assignment to be submitted.
The student has submitted an assignment, but you haven't assigned a grade. This link is turquoise in color.
You'll see the grade sent to the student. Note that multiple choice questions are automatically graded when the student submits them.