How do I exclude a grade for a specific student?
Go to Gradebook.

Select the Gradebook tool from the Tool Menu of your site.
For the Gradebook item that you want to excuse, select the down arrow within the cell for the student's grade and choose Excuse/Include Grade.
The individual grade will be excluded from course grade calculations.
Note: Excluded grade cells will depict a score with a strike-through font (horizontal slash). If the gradebook item corresponding to the excluded cell originates from Gradebook (e.g., and not from Assignments, Tests & Quizzes, etc.), a calculator icon with a diagonal line through it will also display. (Excluded cells for gradebook items originating from Assignments, Tests & Quizzes, etc. will continue to depict a lock icon.)