First and foremost, we thank the graduate TAs who participated in and contributed to this study. We also thank the director, staff, and undergraduate learning and research assistants associated with the Bio1 program for supporting this research. We are thankful for constructive comments on drafts from Jennifer Momsen, Terry Derting, and Paula Soneral. This material has IRB approval (MSU, IRB#X07-1196) and is based upon work supported by the National Science Foundation under grant number DUE-0736928. Funding was also provided by the Future Academic Scholars in Teaching program at Michigan State University.