We study on-the-job learning among classroom teachers, especially learning skills from coworkers. Using data from a new field experiment, we document meaningful improvements in teacher job performance when high-and low-performing teachers working at the same school are paired and asked to work together on improving the low-performer's skills. In particular, pairs are asked to focus on specific skills identified in the low-performer's prior performance evaluations. In the classrooms of low-performing teachers treated by the intervention, students scored 0.12 standard deviations higher than students in control classrooms. These improvements in teacher performance persisted, and perhaps grew, in the year after treatment. Empirical tests suggest the improvements are likely the result of low-performing teachers learning skills from their partner. " Gary Becker (1962) Can employees learn job skills from their coworkers? Whether and how peers contribute to on-the-job learning, and at what costs, are practical questions for personnel management.Economists' interest in these questions dates to at least Alfred Marshall (1890) and, more recently, Gary Becker (1962) and Robert Lucas (1988). Yet, despite the intuitive role for coworkers in human capital development, empirical evidence of learning from coworkers is scarce. 2 In this paper we present new evidence from a random-assignment field experiment in U.S. public schools: low-performing classroom teachers in treatment schools were each matched to a high-performing colleague in their school, and pairs were encouraged to work together on improving their teaching skills. We report positive treatment effects on teacher productivity, as measured by contributions to student achievement growth, particularly for low-performing teachers. We then test empirical predictions consistent with peer learning and other potential mechanisms.While there is limited evidence on learning from coworkers specifically, there is a growing literature on productivity spillovers among coworkers generally. Morreti (2004) and Battu, Belfield, and Sloane (2003) document human capital spillovers broadly, using variation between firms, but without insight to mechanisms. Several other papers, each focusing on a specific firm or occupation as we do, also find spillovers; the apparent mechanisms are shared production opportunities or peer influence on effort (Ichino and Maggi 2000, Hamilton, Nickerson and Owan 2003, Bandiera, Barankay and Rasul 2005, Mas and Moretti 2009, Azoulay, Graff Zivin, and Wang 2010. Moreover, these spillovers may be substantial. Lucas 2 We are focused in this paper on coworker peers and learning on-the-job. A large literature examines the role of peers in classroom learning and other formal education settings (for a review see Sacerdote 2010). 2(1988) suggests human capital spillovers, broadly speaking, could explain between-country differences in income.One empirical example of learning from coworkers comes from the study of classroom teachers. Jackson and Bruegma...

We studied chlorpyrifos, an insecticide present in a commercial dip for treating ectoparasites in dogs, to estimate the amount of transferable residues that children could obtain from their treated pets. Although the chlorpyrifos dip is no longer supported by the manufacturer, the methodology described herein can help determine transferable residues from other flea control insecticide formulations. Twelve dogs of different breeds and weights were dipped using the recommended guidelines with a commercial, nonprescription chlorpyrifos flea dip for 4 consecutive treatments at 3-week intervals (nonshampoo protocol) and another 12 dogs were dipped with shampooing between dips (shampoo protocol). The samples collected at 4 hr and 7, 14, and 21 days after treatment in the nonshampoo protocol averaged 971, 157, 70, and 26 µg chlorpyrifos, respectively; in the shampoo protocol the samples averaged 459, 49, 15, and 10 µg, respectively. The highest single sample was about 7,000 µg collected at 4 hr. The pretreatment specific activities in the plasma of the dogs were about 75 nmol/min/mg protein for butyrylcholinesterase (BChE), and 9 nmol/min/mg protein for acetylcholinesterase (AChE). BChE was inhibited 50-75% throughout the study, and AChE was inhibited 11-18% in the nonshampoo protocol; inhibition was not as great in the shampoo protocol. There was no correlation (p ≤ 0.05) between length of hair and residues measured that would explain the residue differences among dogs. Transferable residues had largely dissipated during the three weeks after treatment, with the largest decrease occurring during the first week. Greater plasma ChE inhibition was observed at 7 days than at 4 hr, probably reflecting the bioactivation of chlorpyrifos to chlorpyrifos-oxon. Plasma cholinesterase activity did not return to control levels during the 3-week period. The differences between the shampoo and nonshampoo protocols were explained by differences in the techniques of the dip applicators.

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