Does Lengthening the School Day Increase School Value-Added? Evidence from a Mid-Income Country

Many mid-income countries face a significant and challenging problem of low educational achievement. This research looks at a Full-Time Primary Schools Programme implemented in Mexico, to work out if extending the time pupils spend at school can enhance skills in language and mathematics. The results of matching plus difference-in-differences point to a positive impact on schools value-added. The effects are concentrated among poorer schools, with gains after policy adoption of 0.11 standard deviations (SD) in both subjects. However, quantile regressions show that the lowest-performance schools are not benefiting from longer school days, posing questions on programme effectiveness to improve the achievement of those who are more in need. Analysis of causal channels suggests that gains reported by the programme do not come from changes in the composition of teachers and pupils in treated schools, and that richer schools are more prone to devote the extra-time of instruction to non-core subjects, notably sports and arts.