Teachers are the most important factor in helping children succeed academically, but it’s principals who hire, support, and develop teachers. Principals see quality teaching through an organizational lens; they can support teachers by pairing them with a mentor teacher, creating opportunities for them to observe classrooms in other schools, provide direct and helpful feedback, as well as organize teacher teams to empower educators to study data. Having good principals is also considered the most cost-effective lever to improve student learning at scale.