Grading schemes translate the student's percentage score to another grade scale. This could be an Alpha scale (A-F) or a GPA scale (4.0). To add a scale to your course:
Video
Text instructions
Go to your course Settings
On the Course Details screen scroll to the Grade Scheme option
Once the option to Enable course grading scheme is selected a dropdown menu will apear with the precreated scheme.
From the dropdown menu select the scheme you want to use.
The scheme will not be previewed for your review. But you can select the View/Edit button
This would produce a pop-up with a preview of the scheme.