We thank Tala Araghi and Jingyi He for their work during the early stages of this project to identify potential participants. We thank the instructors and undergraduates who took the time to participate in these studies. This project was supported by the National Science Foundation (NSF; award no. 00035931). C.A.B. was supported by an National Science Foundation (NSF) Graduate Research Fellowship under Grant no. 026257-001 and K.M.C. was supported by an NSF CAREER award (no. 00037072). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF.