Many countries, American jurisdictions and charter schools have recently embraced longer school days or more time devoted to core academic classes. Recent research generally supports the notion that additional time raises achievement, though difficulties isolating an exogenous source of variation raise questions about the strength of much of the evidence. Moreover, it seems likely that the magnitude of any causal link between achievement and instruction time depends upon the quality of instruction, the classroom environment, and the rate at which students translate classroom time into added knowledge. In this paper we use panel data methods to investigate the pattern of instruction time effects in the 2009 Programme for International Student Assessment (PISA) data. The empirical analysis shows that achievement increases with instruction time and that the increase varies by both amount of time and classroom environment. These results indicate that school circumstances are important determinants of the likely benefits and desirability of increased instruction time.
We thank Dan O'Brien for help with the data development and early analytical work and anonymous referees and the editor for thoughtful comments. Greg Branch provided superb research assistance. This research has received support from the Spencer Foundation, the Hewlett Foundation, and the Packard Humanities Institute. The conclusions of this research do not necessarily reflect the opinions or official position of the Texas Education Agency, the Texas Higher Education Coordinating Board, or the State of Texas. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.
It seems likely the magnitude of any causal link between achievement and instruction time depends upon the quality of instruction, the classroom environment and the rate that students translate classroom time into added knowledge. In this article, we use panel data methods to investigate instruction time effects in the 2009 Programme for International Student Assessment data. The empirical analysis shows that achievement increases with instruction time and that the increase varies by both the amount of time and the classroom environment. The results indicate that school circumstances are important determinants of the benefits and desirability of increased instruction time.
It is widely believed that teacher turnover adversely affects the quality of instruction in urban schools serving predominantly disadvantaged children, and a growing body of research investigates various components of turnover effects. The evidence at first seems contradictory, as the quality of instruction appears to decline following turnover despite the fact that most work shows higher attrition for less effective teachers. This raises concerns that confounding factors bias estimates of transition differences in teacher effectiveness, the adverse effects of turnover or both. After taking more extensive steps to account for nonrandom sorting of students into classrooms and endogenous teacher exits and grade-switching, we replicate existing findings of adverse selection out of schools and negative effects of turnover in lower-achievement schools. But we find that these turnover effects can be fully accounted for by the resulting loss in experience and productivity loss following the reallocation of some incumbent teachers to different grades.
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