Across the OECD countries, only one in five students whose parents have low levels of education earns a post-secondary degree, compared with two-thirds of students with at least one parent who has completed tertiary education. The association between social origin and educational attainment has typically been viewed as an indicator of the lack of openness of a society and reflects the degree to which social inequality is transmitted from one generation to the next.

When there is a strong link between social origin and educational attainment, social mobility is limited. If we embrace meritocratic principles, social inequality in educational attainment is a cause for concern; attainment should be a function of skills, motivation, and effort – and consequently independent of social origin.

Do equitable policies reduce social disparities in educational outcomes?

Both researchers and policymakers have wanted to discover whether certain policies help minimize social inequality in education. Much attention has been focused on extending instruction time and the effects that doing so might have on inequality. At school, all children are socialized in a similar manner, and they are exposed to comparable learning environments, irrespective of their socioeconomic backgrounds. Some therefore argue that extending the school day or school year – and thus providing all children with similar learning opportunities for longer periods of time – will reduce social inequality in education.

Some evidence in support of this hypothesis comes from the United States, where achievement gaps between children of different social backgrounds increase during summer vacations. More advantaged children continue to acquire cognitive skills during these breaks, while less advantaged children are unlikely to make progress when school is not in session.

It seems reasonable to assume that expanding instruction time will help to equalize the skills of children from diverse backgrounds. As a result, several countries, including Denmark, Germany, and the Netherlands, have implemented reforms aimed at extending the school day or year.

Unanticipated consequences of extending instruction time

Extending the school day or year is indisputably a powerful policy instrument for increasing the amount of time a child spends learning. However, such reforms may have unintended consequences that run counter to policymakers’ intentions.

A recent study of European countries suggests that boosting the amount of annual instruction time reduces social inequality in student achievement only if the level of social segregation within the education system is low – that is, if children from different social backgrounds are quite evenly distributed across schools. In socially segregated education systems, on the other hand, increased instruction time actually widens the achievement gap, since children from similar socioeconomic backgrounds are clustered in certain schools and thus isolated from children growing up in different circumstances.

“System-wide policy reforms should focus on the education system as a whole and its interrelated subsystems.”

Research indicates that in segregated education systems, underprivileged students face the double handicap of having disadvantaged peers in school and a disadvantaged family environment. Consequently, an increase in annual instruction time will widen achievement gaps between students from different socioeconomic backgrounds. Underprivileged students will be exposed to more adverse learning environments for a longer period of time, while their more privileged peers will benefit from their schools’ social composition and an environment that is generally more conducive to learning.

System-wide policy reforms should be based on evidence of system-specific policy effects

In light of the above, I urge policymakers to consider a systemic approach. System-wide policy reforms should focus on the education system as a whole and its interrelated subsystems. The effects of policy changes may vary depending on certain aspects of the system, such as social segregation within the system. It is particularly important to avoid undertaking system-level reforms based solely on evidence from individual-level analyses that fail to consider the influence of school- and system-level factors on student achievement and educational inequality.

Simply increasing the amount of instruction students receive will not reduce achievement gaps unless students of diverse social backgrounds are evenly distributed across schools. Before adopting a new system-wide policy aimed at reducing educational inequality, it is crucial to take into account the specific characteristics of the system.



Alexander, K. L., Entwisle, D. R., & Olson, L. S. (2001). Schools, achievement, and inequality: A seasonal perspective. Educational Evaluation and Policy Analysis, 23(2), 171–191.

Burger, K. (2016). Intergenerational transmission of education in Europe: Do more comprehensive education systems reduce social gradients in student achievement? Research in Social Stratification and Mobility, 44, 54–67.

Burger, K. (2016). A transdisciplinary approach to research on early childhood education. GAIA – Ecological Perspectives for Science and Society, 25(3), 197–200.

Burger, K., & Walk, M. (2016). Can children break the cycle of disadvantage? Structure and agency in the transmission of education across generations. Social Psychology of Education, 1–19.

OECD (2012). Education at a glance: Highlights. Paris: OECD Publishing.

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