This study investigates whether unannounced quizzes can improve student learning outcomes in introductory microeconomics courses. Using data from 257 students and controlling for section-bysemester fixed effects, we find that unannounced quizzes significantly improve final exam performance. Moreover, quiz performance predicts exam success even when quiz scores do not count toward the final grade. This suggests that the results are driven by a continuous preparation effect—students maintaining regular study habits in anticipation of surprise assessments—rather than by immediate grade incentives. However, under a “best-of-N” quiz grading policy, we identify a trade-off. While this policy provides a safety net for lower-performing students (consistent with mastery learning principles), it inadvertently encourages strategic slacking among high achievers. Once these students have secured the maximum possible quiz credit, they rationally reduce their effort. These findings underscore the importance of designing assessment structures that sustain motivation across the full spectrum of student ability levels.
