Essays on the economics of teachers and teaching [electronic resource]
Keywords: Education.

Across three papers I study how differences in the quality and quantity of classroom instruction contribute to differences in what students learn in school. The first two papers focus on teachers—specifically what gives rise to differences between teachers in student learning. The third paper focuses on the quantity of instruction time students receive. The results are immediately relevant to both ongoing education policy debates about teaching quality and the day-to-day management of a large workforce. First, in paper one, I study the effects of a labor-replacing computer technology on the productivity of classroom teachers. In a series of field-experiments, teachers were provided computer-aided instruction (CAI) software for use in their classrooms; CAI provides individualized tutoring and practice to students one-on-one. In math classes, CAI reduces by one-fifth the variance of teacher productivity, as measured by student test score gains. The smaller variance comes both from productivity improvements for otherwise low-performing teachers, but also losses among high-performers. The change in productivity partly reflects changes in teachers' level of work effort and teachers' decisions about how to allocate class time. Second, I study whether and how teachers' assigned job tasks—the basic instructional practices they are asked to use in the classroom—affect the returns to math skills in teacher productivity. The empirical results demonstrate the value distinguishing between workers' skills and the job tasks to which those skills are applied, as in Acemoglu and Autor (2011). I use data from a randomized-trial of different approaches to teaching early-elementary math, each approach codified in a set of day-to-day tasks for teachers; the data include a baseline test of each teacher's math skills—knowledge of math concepts, procedures, and pedagogy. Teacher productivity, as measured by contributions to student math test score growth, is increasing in math skills when teachers are asked to follow conventional "direct-instruction" practices which rely on teachers explaining and modeling math rules and procedures for their students. The relationship is weaker, perhaps even negative, when teachers use newer "student-led" practices. The difference in productivity is pronounced for the high-skilled (top-tercile) teachers where the difference between direct-instruction and student-led is 0.13-0.16 student standard deviations. Additionally, assigning teachers to use student-led practices reduces the total variation in productivity by one-third or more compared to direct-instruction. Finally, for students whose math skills lag expectations, public schools often increase the fraction of the school day spent on math instruction. Studying middle-school students and using regression discontinuity methods, I estimate the causal effect of requiring two math classes—one remedial, one regular—instead of just one class. Math achievement grows much faster under the requirement, 0.16-0.18 student standard deviations. Yet, one year after returning to a regular one-class schedule, the initial gains decay by as much as half, and two years later just one-third of the initial treatment effect remains. This pattern of decaying effects over time mirrors other educational interventions—assignment to a more skilled teacher, reducing class size, retaining students—but spending more time on math carries different costs. One cost is notable, more time in math crowds out instruction in other subjects.