Spending more time at school benefits the best-performing students disproportionately, according to a study.
The researchers used data from the Early Childhood Longitudinal Study – Kindergarten Cohort (ECLS-K). The ECLS-K followed the cohort class of 1998-1999 from kindergarten to their eighth grade, while the present study used the data from the autumn and spring semesters in the 1998-99 school year during kindergarten for analysis. This included more than 20,000 children from 1,000 kindergarten programs in schools for children who entered kindergarten in 1998. Children were given math and reading tests in the fall and spring. Because there was essentially random variation in when these tests were delivered, there were variations in the amount of instructional time between the two tests. The researchers used this to analyze the progress made, but also the difference in progress among the different percentiles within the class. They found that:
- On average, reading scores increase by 1.6 test score standard deviations (SD) during a standard 250 day school year.
- However, readers in the bottom 10% increased by only 0.9 test score SD, while those in the top 10% increased by 2.1 test score SD.
- A similar result was found for mathematics.
The authors suggest that policymakers, practitioners, and analysts must consider the average and distributional impacts of educational inputs and interventions.
Source (Open Access): Hayes, M.S., & Gershenson, S. (2016). What differences a day can make: Quantile regression estimates of the distribution of daily learning gains (IZA Discussion Paper No. 9305). Bonn, Germany: Institute for the Study of Labor.