And to explain to you how I visualize the concept of an expert teacher I want to share a film trailer named as "Stand and Deliver (1988)" which is about a mathematics teacher and his unusual teaching methods and classroom management techniques that help his desperate students in a rural school pass the advanced calculus exam.
https://www.youtube.com/watch?v=sG-Cxs8eYkI
As methods of imaging the brain improve, neuroscientists and educators can now identify changes in children's brains as they learn, and start to develop ways of personalizing instruction for kids who are falling behind.