Until recently, states focused on ensuring the presence of a "highly qualified teacher" in every classroom. Under the 2001 reauthorization of the Elementary and Secondary Education Act (ESEA), known as No Child Left Behind (NCLB), this title described a teacher holding at least a bachelor's degree and the appropriate state license and…

Improving teacher preparation is critical to long-term improvement in teacher quality. More than 200,000 new teachers enter classrooms each year. Increasing student enrollment, the retirement of baby boom generation teachers, and high attrition in their first five years (between 40 and 50 percent of new teachers leave the profession) have…

Teachers have the greatest school-based effect on the achievement of any child in their classrooms, but highly effective principals can positively affect the achievement of every student in their schools. The difference between a highly effective principal and an average one is equal to two-to-seven months of extra learning per year for each child…