C.S. Lewis (of Narnia fame) on peer learning:
It often happens that two schoolboys can solve difficulties in their work for one another better than the master can. The fellow-pupil can help more than the master because he knows less. The difficulty we want him to explain is one he has recently met. The expert met it so long ago he has forgotten.
I’ve always been a big proponent of peer teaching and peer mentoring in medicine. I also often wonder if I’m getting worse at teaching the basics as I get older.