The retention benefits of cumulative versus non-cumulative midterms in introductory biology may depend on students' reasoning skills.

Assessment has long played an important role as a measurement tool of student mastery over course content. However, testing has also been shown to be an effective learning tool. Cumulative testing, in which all material from the entire learning period is covered, has been assumed to be effective, yet few studies have explicitly tested its effectiveness compared to non-cumulative testing. Studies in psychology and mathematics courses suggest that cumulative final exams increase long-term retention of information, and cumulative testing during the semester can increase cumulative final exam performance and long-term retention. Because frequent testing has also been shown to increase student learning, the purpose of this quasi-experimental study is to investigate the effects of cumulative versus non-cumulative midterms on student learning in a course that uses frequent assessment. In this study, one section of an introductory biology course for non-majors was given seven cumulative midterms, with about half of the questions drawn from previous units and the rest covering the current unit. The other section was given seven non-cumulative midterms that focused on current material while other course characteristics were held constant. Student performance on a common, cumulative final exam and a retention exam five months later were compared. Midterm format had no effect on final exam performance, contradicting the few studies done in psychology and mathematics courses. Thus, there may be no additional benefit of cumulative testing if exams are given frequently. Cumulative midterms appeared to increase retention after five months, but only for students who entered the course with low reasoning skills. Interestingly, students with high reasoning skills appeared to retain more from the course if they were given non-cumulative midterms. Possible explanations and ideas for future research are discussed