Also there is a different psychological dynamic in small groups... The teacher naturally knows and cares more about the student, and the student feels socially accountable (ie. "I want to make (so-and-so) proud." And, in a real sense, the master and apprentices are a team.

And this isn't the "we need more money and teachers" argument I'm making, just that the large-group lecture format only works well for certain stages of learning and types of learners.