Green’s book is about a more recent effort, spearheaded by a small handful of teaching revolutionaries, to improve the teaching of teaching. The common belief, held even by many people in the profession, that the best teachers are “natural-born” is wrong, she writes. The common characteristic of her main characters is that they have broken down teaching into certain key skills, which can be taught.

“You don’t need to be a genius,” Green told me recently. “You have to know how to manage a discussion. You have to know which problems are the ones most likely to get the lessons across. You have to understand how students make mistakes — how they think — so you can respond to that.” Are these skills easier for some people than others? Of course they are. But they can be taught, even to people who don’t instinctively know how to do these things.

One of Green’s central characters is a woman named Deborah Loewenberg Ball, who began her career as an elementary school teacher and is now the dean of the University of Michigan’s School of Education. “Watching Deborah teach is like listening to chamber music,” Green quotes an admirer. But she didn’t start out that way. She struggled as a young teacher, and, as she became a better teacher, she began to codify, in her own mind at first, the practices that made her successful. And she asked herself, “Why hadn’t she learned any of this before?”

Green has a chapter about why schools of education value things other than the actual teaching of teachers. But the University of Michigan under Ball is one place that is trying to reverse that trend, not just at Michigan but across the country. Ball is pushing the idea that teachers should be prepared to teach — that they should have the tools and the skills — when they walk into that classroom on the first day on the job. That is rarely the case right now.

“We need to shift teaching to be like other fields where you have to demonstrate proficiency before you get a license,” Ball told me not long ago. “People who cut hair and fly airplanes get training that teachers don’t get.”