A grading scheme is a set of criteria that measures varying levels of achievement in a course. On a course level, instructors can apply grading schemes to both students' final grades and individual assignments.
For most courses, you will want to use the University of Minnesota Letter Grade Scheme which is the approved undergraduate grading scheme for the University. Some colleges have their own grading schemes that are available in their courses. Confirm with your college's Academic Technology Contacts for what grading scheme you should use with your course.