Research shows good teaching makes a big difference in how much kids learn. But the United States lacks an effective system for training new teachers or helping them get better once they’re on the job. This documentary examines why, and asks what it would take to improve American teaching on a wide scale. We meet researchers who are trying to understand what makes teaching complex, and how to determine whether someone is ready to be a teacher. We also visit U.S. schools that are taking a page from Japan and radically rethinking the way they approach the idea of teacher improvement.