Ten Years After the OECD's Warning: Bias Against Boys in Schools Still Ignored

In 2015, the OECD published The ABC of Gender Equality in Education, one of the first major international studies to highlight a consistent pattern in classroom assessment: when teacher grading was compared against standardized external tests, boys systematically received lower marks than girls, even when their performance was identical ^[1]. Teachers "generally award girls higher marks than boys," the report stated, especially in the language of instruction. The OECD flagged this as a hidden inequality, one that could shape long-term educational outcomes.

Follow-up OECD studies confirmed that this was not an isolated finding. Later analyses pointed out that teachers often perceive girls as more motivated, disciplined, or diligent, and that these perceptions appear to influence the grades awarded, particularly in subjects where marking criteria allow for subjective judgment ^[2]. In other words, the gap was not explained by ability, effort, or test results -- it was a matter of bias. While small differences might seem insignificant on an individual basis, the cumulative effect over years of schooling can shape students' confidence, course enrollment, and eventual career paths.

Economists and education researchers have since reinforced the OECD's conclusions with large-scale studies across multiple countries. Lavy and Sand's analysis of blind versus non-blind exam grading demonstrated a clear disparity: when teachers knew the student's identity, girls' grades were higher; when tests were graded blindly, the gender gap disappeared or even reversed ^[3]. This suggests that the difference arises not from performance but from subjective teacher perceptions.

Terrier's work in France found the same pattern in mathematics, a subject often considered "objective." Girls received higher grades from teachers than boys with the same standardized scores. Crucially, this advantage carried over into later years, affecting track placement, course choice, and confidence in STEM subjects ^[4]. A large study in Greece, published by the National Bureau of Economic Research (NBER), showed that these grading biases have measurable effects on higher education and labor market outcomes. Boys systematically disadvantaged by teacher assessments were less likely to qualify for elite universities and certain career pathways. Even more striking, the study found that grading bias is persistent at the teacher level: some teachers consistently over-reward girls and under-reward boys, year after year ^[5].

In the United States, Cornwell, Mustard, and Van Parys showed that non-cognitive behavior assessments play a major role in the discrepancy. Girls tend to be rated as more attentive, cooperative, and disciplined, and these impressions strongly influence grades. Once test scores were controlled for, teachers consistently awarded higher marks to girls, suggesting that classroom behavior -- rather than academic mastery -- was driving much of the difference ^[6]. The implication is clear: boys may be academically capable, but are held back by teachers' subjective evaluations of their behavior.

Taken together, these studies present a consistent and troubling picture across Europe and North America. When grades are based on external, anonymous exams, boys perform at least as well as girls. But in day-to-day school assessments -- the kind that determine report cards, promotion to higher-level courses, and ultimately university access -- boys are at a structural disadvantage. The discrimination is subtle, but its consequences are long-lasting: reduced confidence, fewer opportunities, and systematic underrepresentation of boys in higher education relative to their measured ability.

Despite the weight of evidence, governments have done little to act. When gaps appear to disadvantage girls -- for example, in STEM participation -- policymakers have introduced scholarships, targeted programs, and nationwide campaigns. Yet when gaps are shown to disadvantage boys, the response has been minimal. The OECD itself has largely restricted its recommendations to "raising awareness" and encouraging teacher training that touches on unconscious bias, but no country has implemented a direct corrective mechanism to ensure grading fairness ^[2].

This inaction is all the more striking because grading bias is not a minor issue. University admissions, scholarships, and even job applications often rely on grade point averages and teacher recommendations. If boys are consistently marked down compared to equally able girls, then half the population is competing on systematically unfair terms. The OECD flagged this nearly a decade ago, yet the inequality persists with little sign of change.

The broader consequence is that boys are steadily falling behind in higher education. Across the OECD, women now make up a majority of university students. While some celebrate this as progress for gender equality, the hidden role of discriminatory grading in shaping these trends is rarely acknowledged. If left unaddressed, the grading bias identified by the OECD may continue to skew educational outcomes for years to come, with profound effects on labor markets, professional fields, and society at large.

^[1] OECD (2015), The ABC of Gender Equality in Education. Link

^[2] OECD (2019), OECD Skills Strategy 2019, Chapter on Gender and Skills. Link

^[3] Lavy, V. & Sand, E. (2018). "On the Biases of Teachers' Grades." Journal of Labor Economics. Link

^[4] Terrier, C. (2020). "Boys Lag Behind: How Teachers' Gender Biases Affect Student Achievement." Economics of Education Review. Link

^[5] NBER (2022). "Teachers' Grading Bias and Long-Term Outcomes." Link

^[6] Cornwell, C., Mustard, D., & Van Parys, J. (2013). "Noncognitive Skills and the Gender Disparities in Test Scores and Teacher Assessments." Journal of Human Resources. Link