A study by Huebener and colleagues examined whether increasing the amount of time pupils spend in the classroom affects their performance.
The authors used PISA scores to analyse the effect of increasing the time spent in class by two hours per week over a five-year period for ninth-grade students in Germany (average age = 15 years old). During the additional classroom time, pupils were taught new content.
Their findings indicate that while increasing the time spent in class did improve pupils’ average performance, effect sizes were small. The increase in lesson time was shown to increase average PISA test scores in reading, maths and science (effect size between +0.04 and +0.06 for one additional hour per week). However, these results differ according to pupil ability, with a widening gap in performance between low- and high-performing pupils. The researchers suggest this is because the additional teaching time was used to teach new content, and that lower-performing pupils may not be able to cope with this additional content. They recommend that when policymakers consider adding additional classroom time, they consider how this time is spent. Different pupils have different learning needs, so the content of the extra lessons, rather than the time, is more important to improving pupil performance.
Source: Increased instruction hours and the widening gap in student performance (August 2017), Labour Economics, Volume 47