This research was originally inspired by discussions during the Teagle-funded Collegium on Student Learning led by the Accredited Colleges of the Midwest and by work with students as part of an NSF S-STEM Biologists for the Future grant to A. W., D. A., and K. G. (NSF Award # 0727556). This work would also not have been possible without the participation of introductory biology faculty at St. Olaf College as well as a team of Student Fellows (Kelly Hennessey and Sam Bailey-Seiler) within the Center for Interdisciplinary Research at St. Olaf (NSF Program to Enhance Mathematical Science for the 21st Century DMS-1045015 and DMS-0354308). We are grateful to Mary Walczak for providing valuable feedback on this paper.