Constructive evaluation encourages students to exert maximum effort by emphasizing their strengths, identifying concrete ways for them to improve, and providing them with positive reinforcement for progress. Mandatory grading encourages teachers to evaluate their students in ways that do not promote critical thinking and long-term retention. For example, teachers of large classes may assign grades based on students' ability to memorize facts. Tests based on factual information are simple and quick to score, but they do not foster critical thinking. Their behavior in preparing for a test depends on the nature of the test.
Students develop learning styles that they expect to yield good grades.
Some teachers feel proud when a high percentage of their students fail. They want others to believe that a high failure rate signifies a difficult course and an intelligent teacher. To a large extent, they succeed. Some teachers believe that giving students low grades adds luster to their own reputations. Such teachers may choose to include excessively difficult material in their courses simply to enhance their own self-importance.