Reducing the weight of low exam scores may raise average grades but does not appear to impact equity gaps

Students interpret grades as signals of their strengths, and grades inform students' decisions about majors and courses of study. Differences in grades that are not related to learning can impact this judgment and have real-world impact on course-taking and careers. Existing work has examined how an overemphasis on high-stakes exams can create equity gaps where female students and Black, Hispanic, and Native American students earn lower grades than male students and Asian and white students, respectively. Yet, minimal work has examined how the weighting of individual midterm exam scores can also contribute to equity gaps. In this work, we examine how three midterm exam score aggregation methods for final grades affect equity gaps. We collected midterm exam data from approximately 6,000 students in an introductory physics course over 6 years at a large, research-intensive university. Using this data set, we applied common midterm exam score aggregation methods to determine their impact on aggregated midterm exam grades: dropping the lowest midterm exam score, replacing the lowest midterm exam score with the final exam score if higher, and counting the highest midterm exam score more in the final grade calculation than the lowest midterm exam score. We find that dropping the lowest midterm exam score resulted in the largest increase in final grades, with students with lower grades benefiting the most. However, we find limited evidence that alternative midterm exam aggregation methods could close equity gaps. Implementing the alternative midterm exam aggregation methods examined here may be useful for instructors wanting to raise course grades or give lower-scoring students a boost. However, they do not appear to be effective in reducing equity gaps.