I study how teachers’ assigned job tasks—the practices they are asked to use in the classroom—affect the returns to math skills in teacher productivity. The results demonstrate the importance of distinguishing between workers’ skills and job tasks. I examine a randomized trial of different approaches to teaching math, each codified in a set of day-to-day tasks. Teachers were tested to measure their math skills. Teacher productivity—measured by student test scores—is increasing in math skills when teachers use conventional “direct instruction”: explaining and modeling rules and procedures. The relationship is weaker, perhaps negative, for newer “student-led” methods.

We document measurable, lasting gains in student achievement caused by a change in teachers' evaluation incentives. A short-lived rule created a discontinuity in teachers' incentives when allocating effort across their assigned students: students who failed an initial end-of-year test were retested a few weeks later, and then only the higher of the two scores was used when calculating the teacher's evaluation score. One year later, long after the discontinuity in incentives had ended, retested students scored 0.03σ higher than nonretested students. Otherwise identical students were treated differently by teachers because of evaluation incentives, despite arguably equal returns to teacher effort.

Teacher performance evaluation has become a dominant theme in school reform efforts. Yet, whether evaluation changes the performance of teachers, the focus of this paper, is unknown. Instead, evaluation has largely been studied as an input to selective dismissal decisions. We study mid-career teachers for whom we observe an objective measure of productivity—value-added to student achievement—before, during, and after evaluation. We find teachers are more productive in post-evaluation years, with the largest improvements among teachers performing relatively poorly ex-ante. The results suggest teachers can gain information from evaluation and subsequently develop new skills, increase long-run effort, or both.

This paper reports on a field experiment in 82 high schools trialing a low-cost intervention in schools’ operations: teachers working in the same school observed and scored each other’s teaching. Students in treatment schools scored 0.07 student standard deviations higher on math and English exams. Teachers were further randomly assigned to roles—observer and observee—and students of both types benefited, observers’ students perhaps more so. Doubling the number of observations produced no difference in student outcomes. Treatment effects were larger for otherwise low-performing teachers.

We examine how employers learn about worker productivity in a randomized pilot experiment which provided objective estimates of teacher performance to school principals. We test several hypotheses that support a simple Bayesian learning model with imperfect information. First, the correlation between performance estimates and prior beliefs rises with more precise objective estimates and more precise subjective priors. Second, new information exerts greater influence on posterior beliefs when it is more precise and when priors are less precise. Employer learning affects job separation and productivity in schools, increasing turnover for teachers with low performance estimates and producing small test score improvements.

Using Student Performance Data to Identify Effective Classroom Practices by John H. Tyler, Eric S. Taylor, Thomas J. Kane and Amy L. Wooten. Published in volume 100, issue 2, pages 256-60 of American Economic Review, May 2010

Online college courses are a rapidly expanding feature of higher education, yet little research identifies their effects relative to traditional in-person classes. Using an instrumental variables approach, we find that taking a course online, instead of in-person, reduces student success and progress in college. Grades are lower both for the course taken online and in future courses. Students are less likely to remain enrolled at the university. These estimates are local average treatment effects for students with access to both online and in-person options; for other students, online classes may be the only option for accessing college-level courses.