“There are a number of things that influence the grades that one gets, and it’s not always what we think it is,” Bull said. For example, many classes in the U.S. assign a grade by tallying up cumulative points on all tests, quizzes, assignments, and projects throughout the semester. But quizzes given early in the course tend to benefit those students who come into the class with prior knowledge of the subject. If a student has a mother who’s a chemist, for example, or a father who’s a history buff might perform better on early assessments because she’s familiar with the material.