  We analyze the effectiveness of working in pairs on the Conceptual Survey of
Electricity and Magnetism test in a calculus-based introductory physics course.
Students who collaborated with a peer showed significantly larger normalized
gain on individual testing than those who did not collaborate. We did not find
statistically significant differences between the performance of students who
were given an opportunity to formulate their own response before the peer
discussions, compared to those who were not. Peer collaboration also shows
evidence for co-construction of knowledge. Discussions with individual students
show that students themselves value peer interaction. We discuss the effect of
pairing students with different individual achievements.
