The purpose of standards-based grading is to report what students know and are able to do. Averaging, while a fixture in most grading systems, does not represent an accurate picture of where a student is in his/her learning. A student who struggles in a class at the beginning of a grading period and receives poor grades, but who keeps working and by the end of the grading period can clearly demonstrate competence in the subject, should receive a grade that reflects that competence.
Consider two students, Stewart and Maria. Stewart earns the following scores: 85, 85, 85, 85, 85, 85, 85, 85 and 85. The average is not difficult to calculate in a traditional system; Stewart’s grade is posted as a B. Maria struggles in math and turns in this performance: 50, 60, 65, 70, 80, 85, 90, 90, and 90. Her mean score of a little over 75 would result in a C on her report card, yet it is obvious that Maria now understands the math even though she struggled in the beginning.