Being older among peers at school

Children start school at different stages of their social, emotional, and cognitive development. This paper investigates the effect of being one year older among peers on a series of relevant outcomes, exploiting differences in school starting age, using administrative records of every public-school student in Portugal.

The paper shows that starting school 1-year later leads to significantly better performances in Math and Language exams in fourth, sixth and ninth grade. These differences mostly reflect cognitive maturity gaps, typical of children this age.

However, certain institutional mechanisms make school starting age matter to the individual through other margins besides measurable achievement differences. Older school entrants also have a substantially lower probability of repeating grades throughout primary, lower, and upper secondary education. Even for students with the same exam scores, young students are substantially more likely to be retained in the same grade.

Older students also have a lower probability of dropping out from school, are more likely to enroll in the academic track and in more scientific curricula in high school, have higher application scores to access public higher education and enroll in more selective undergraduate courses.

Importantly, public policy responses should be nuanced. Children who start school a year later typically remain in pre-school environments whose quality for learning are more strongly correlated with family background. Both parents and policymakers should thus appropriately weigh costs associated with an additional year of childcare outside formal schooling environments and shorter work careers. Policymakers can consider ex ante measures, namely early childhood interventions aimed at addressing school readiness gaps across children from different socioeconomic groups and adjustments to academic curricula.

Click here to go to the paper by Gonçalo Lima, Luís Catela Nunes, Ana Balcão Reis, and Maria do Carmo Seabra.