Still another reason for the better performance of the weekly quiz group might be that quizzes create a lot of extrinsic motivation for the students since students want to obtain good grades in the course; therefore, they try hard and spend a lot of time preparing for the quizzes (Dustin, 1971; Standlee & Popham, 1960). Although, motivation and interest are the incentives for learning, Zarei (2008) argues that ―motivation is not always the cause of good grades; it may well be the result of them. Quizzes increase course grades by supplying motivation, and motivate students to study by improving their grades‖ (pp. 5-6). In addition, when students take tests regularly, they become accustomed to the tests, and this reduces their sense of test anxiety. Therefore, when taking the final examination, they experience lower levels of debilitative test anxiety compared with those who take tests less frequently. The lower levels of debilitative test anxiety may, in turn, boost the learners‘ test performance.