Background: Experimental design and analyses require an understanding of variation, a critical concept for STEM students. DrosoVEDA addresses an unmet need to develop and evaluate an undergraduate laboratory curriculum that provides students with a deep understanding of biological variation and statistics. Lycoming College has a diverse student population, with 31% students from the global majority. Research Question: Can a 3-week lab curriculum redesign improve diverse students’ understanding of biological variation and statistics? Study design/methods: Three new 3-hour lab exercises were developed to address sources of variation (organismal, systemic/experimental, and measurement error); the importance of appropriate sample sizes and unbiased sampling methods; the relationships between numeric and visual representations of means, standard errors, t statistics, and significant differences; the verbal meaning of terms in the t statistic equation; and when t tests are and are not appropriate. A 16-question assessment tool was adapted from a zebrafish-based curriculum (BioVEDA; Dewey et al. 2020; Hicks et al. 2020), and administered as a pre- and post-test. Drosophila were reared at 18 ºC or 25 ºC, and students chose sampling strategies and used microscopes to measure the length of the L3 vein. Students discussed strengths and weaknesses of different ways to represent and compare the data, graphically and statistically. Data: 64 students in 4 lab sections took the pretest during Week 1, and again at semester’s end for a post-test. Within-student pre-versus-post paired t tests showed highly significant learning gains, with p values of 9.5e-7 for one instructor and 0.004 for another instructor. Average pretest scores were 6.73 (sd 2.74, SEM 0.428) and posttest scores were 8.81 (sd 3.00, SEM 0.501), confirming that DrosoVEDA works. Conclusion: The DrosoVEDA curriculum improved student comprehension of variation, graphing, and statistical summary and testing. Further question-by-question analysis will guide the next round of revisions to the lab curriculum.
