The cognitive outcomes of mastery learning are mainly related to increase in student excellence in a subject. According to one study, applying the strategies of mastery learning in a class resulted in the increase of students with the grade of A from 20 percent to 80 percent (about two standard deviation), and using the formative evaluation records as a base for quality control helped the teacher to improve the strategies and increase the percent of students with a grade of A to 90% in the following year.