Several studies attest to the value of communication-intensive activities for increasing student understanding of essential course material.  We'd like to draw your attention to two:
 

1.  The Harvard Assessment Seminars (1992)

2.  Physics and Peer Instruction at Harvard.  Crouch and Mazur.  "Peer Instruction: Eight Years of Experience and Results" (1999).  http://mazur-www.harvard.edu/