you r very much right in ur words. Here, i would emphasize on the fact that some teachers keep student at arm's lenght thus creating a kind of communication gap. Teacher's foremost responsbility is to impart knowledge to students in an intimate and convenient manner.
But i am extremly sorry to say at times when student intends to explain extra dipiction about something, either they are categorically discourged or ignored instead of giving them due encourgement.