Twenty-five years ago, the still-resonant report "A Nation at Risk" urged schools to add more time--an hour to the usual six hour day and 20-40 days to the typical 180-day ear--to ward off a "rising tide of mediocrity" in American education. Today, city, school, state, and national leaders are engaged in a renewed effort to do…

This paper examines whether teachers in schools serving students from high-poverty backgrounds are as effective as teachers in schools with more advantaged students. The question is important. Teachers are recognized as the most important school factor affecting student achievement, and the achievement gap between disadvantaged students and their…