Book excerpt: The strongest influence on whether a student learns (and how much) is the teacher. Never mind fancy facilities, new technology, top curricula, or more school spending—research shows that the intelligence, skill, and dedication of the instructor is two to three times as important as any other contribution to student outcomes. If we want to improve schools, we must raise the quality of teachers. Yet credentials, degrees, years on the job have little to do with classroom excellence. Fascinating investigations have recently given us clearer pictures of what a successful teacher looks like. Now leading schools are beginning to hire and mentor teachers differently, with a clear-eyed focus on their demonstrated ability to transfer knowledge to their students. New techniques for measuring and enhancing the teacher’s capacity to add value in the classroom are the most promising elements in school reform today. Putting them into effect, though, requires wise and brave school leaders. Without bold, sober, demanding principals, few schools will build a truly excellent set of instructors. This book is for public-spirited donors who want to foster educational excellence by elevating teachers and principals. It reviews the latest academic research and on-the-ground experience of reformers and offers practical advice on multiple fronts. It is written for philanthropists and allies active in the field who want to make a positive difference.