Give the definitions for each letter grade. The clearest definitions are numerical. Continue with the syllabus by being very clear about any consequences to grades that will result from absences, missed tests and quizzes, late assignments, or violations of ethical conduct. Keep students informed of their progress throughout the course. If a discrepancy exists between the grade a student thinks he or she has and the number in a grade book, resolve that discrepancy immediately.
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Once a policy is set, apply it equally to all students. Subjective adjustments during or after a course are likely to prove dangerous. Validate grades with an alternative assessment of learning such as a pre-post test or knowledge survey. Grading is communication to both students and to those who later review students. Grading has permanent consequences.