Exclude empty grades
Empty Grades simply indicates that a grade has not been entered in the gradebook. It may be empty because a student has not made a submission or that the teacher has not yet graded the item. Empty grades display as dashes in the Grader Report; they are different than scores of zero. Zeros are calculated, but dashes (empty grades) count towards the overall grade depending on what the teacher in the site has selected.
By clicking Exclude Empty Grades, the teacher is displaying a total that only reflects the graded items in the course, and does the overall grade does not include graded items.