We are grateful to the study participants for their time, and we thank the course instructors for their support in providing the exam problems. We also thank R. Holmgren and G. Light for thoughtful discussions in the early phases of the study. This project was initiated with support by an institutional award from the Howard Hughes Medical Institute for undergraduate biology education under award number 52006934 and the Hewlett Fund for Curricular Innovation from the Weinberg College of Arts and Sciences at Northwestern University. S.K. and A.J.G. were supported by the Undergraduate Research Assistant Program in the Office of Undergraduate Research at Northwestern University. S.M.L. was supported in part by the Faculty Career Development Program at the University of California San Diego.