Teachers and Student Achievement in the Chicago Public High Schools

We estimate the importance of teachers in Chicago public high schools using matched student-teacher administrative data. A one standard deviation, one semester improvement in math teacher quality raises student math scores by 0.13 grade equivalents or, over 1 year, roughly one-fifth of average yearly gains. Estimates are relatively stable over time, reasonably impervious to a variety of conditioning variables, and do not appear to be driven by classroom sorting or selective score reporting. Also, teacher quality is particularly important for lower-ability students. Finally, traditional human capital measures—including those determining compensation—explain little of the variation in estimated quality.