
One of the least-discussed but most consequential issues in education is the quiet, consistent bias boys face in the classroom when it comes to grading. For decades we’ve been told that girls are soaring, and boys underachieve in school because they are careless, disruptive, or simply not as diligent as girls. The implication is that maybe they are just not as smart as the girls. But the research suggests something even more troubling: part of the gap is not about effort or ability at all — it’s about teacher bias.
Evidence from Blind Grading
The best way to test bias is to compare blind evaluations — where teachers don’t know the student’s identity — with everyday classroom grades. Several studies across different countries have done just this, and the results are consistent: teachers tend to grade boys more harshly than girls, even when their performance is the same.
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A large French study led by Camille Terrier compared blind test scores with teacher-assigned grades in middle schools. She found that boys consistently received lower grades from teachers than their anonymous test scores would predict. Strikingly, she estimated that about 20% of the math achievement gap that emerges during middle school could be explained by gender-biased grading. Even more telling, Terrier concluded that without this bias in favor of girls, the gender gap in choosing a science track would be 12.5% larger in favor of boys. In other words, bias wasn’t just present — it was actively reshaping the pipeline of who goes on to advanced study in math and science, with long-term consequences for boys’ educational and career paths.
Similar evidence from Israel, the U.S., and Northern Europe confirms the same pattern: when the work is graded blindly, the boy–girl gap shrinks or disappears. When names are attached, boys lose ground.
Which Teachers Are More Biased?
You might think male teachers would favor boys and female teachers would favor girls. But the evidence paints a more nuanced picture.
Female teachers tend to show stronger pro-girl bias, especially in language and reading. This bias often reflects the stereotype that girls are more diligent and boys are more disruptive, so girls “deserve” higher marks.
Male teachers, on average, are less biased. Some hold traditional stereotypes about boys being better at math or science, but the grading effects are weaker and less consistent.
A Dutch experimental study showed that the biggest driver wasn’t male vs female teachers — it was the strength of the teacher’s gendered beliefs. Teachers with strong stereotypes (regardless of sex) were the ones who showed the most bias.
Still, because most teachers in primary and secondary schools are women — and because women have been found to be more likely to display grading bias and act on gendered stereotypes — the aggregate effect in the system tends to tilt strongly against boys.
Behavior vs. Knowledge
Another factor often at play is behavior. Boys are, on average, more restless and less compliant in the classroom. Research shows teachers sometimes fold these behavioral impressions into grades — rewarding neatness, punctuality, and compliance. This might seem harmless, but it means grades measure more than knowledge or skill: they also reflect how much a student fits the teacher’s ideal. And since boys more often fall outside those expectations, they get marked down.
The Mismatch Between Grades and Tests
It is telling that in almost every developed country, girls now outperform boys in teacher-assigned grades, while boys do just as well — and in some cases better — on blind, standardized tests. This pattern has been documented across Europe, North America, and beyond. In the U.S., for example, boys consistently score higher than girls on the SAT math section, yet girls often finish high school with higher GPAs. In France, Terrier’s research showed that gender bias in grading alone could account for as much as one-fifth of the math achievement gap that emerges in middle school. The contradiction is hard to miss: when evaluation is objective and anonymous, boys hold their ground; when evaluation depends on teacher judgment, boys slip behind. That mismatch should raise alarms because it means the system isn’t only measuring knowledge or ability — it is embedding adult perceptions and stereotypes directly into the record that determines children’s futures.
This bias doesn’t just stop at the classroom door. Grades are the passport to opportunity: they determine who gets into advanced classes, who qualifies for scholarships, and who gains admission to selective universities. A boy who consistently earns lower grades than his test scores warrant is effectively being nudged onto a different trajectory than his female peers. Over time, this means fewer boys in honors programs, fewer in elite universities, and ultimately fewer in high-status professions. The irony is stark — boys demonstrate equal or greater competence on standardized measures, yet are slowly tracked downward by a system that confuses compliance with ability. When entire cohorts of boys are quietly edged out of opportunity in this way, it becomes more than a private injustice. It’s a cultural blind spot with consequences for the workforce, higher education, and even the pool of future leaders.
A Needed Conversation
We’ve had endless debates about girls and STEM. But the evidence is just as clear that boys are being penalized in grading systems that reward compliance and reinforce teacher stereotypes. Acknowledging this is not about putting boys over girls, but about ensuring fairness. A boy who turns in the same quality of work as a girl should receive the same grade.
Anonymous grading, clearer rubrics, and awareness of implicit bias could all help. But the first step is cultural honesty: admitting that boys are often graded down not because they lack ability, but because they don’t conform to the teacher’s expectations.
Boys Are Good and deserve fair treatment.
References
Terrier, C. (2020). Boys lag behind: How teachers’ gender biases affect student achievement. Journal of Public Economics. https://www.sciencedirect.com/science/article/abs/pii/S0272775718307714
Lavy, V. (2008). Do gender stereotypes reduce girls’ or boys’ human capital outcomes? Evidence from a natural experiment. Economic Journal. https://www.sciencedirect.com/science/article/abs/pii/S0047272708000418
Cornwell, C., Mustard, D. & Van Parys, J. (2013). Noncognitive skills and the gender disparities in test scores and teacher assessments: Evidence from primary school. Journal of Human Resources. https://jhr.uwpress.org/content/48/1/236.abstract
Ferman, Brunon. Fontes, Luiz Felipe (2022). Assessing knowledge or classroom behavior? Evidence of teachers. Journal of Public Economics. https://www.sciencedirect.com/science/article/abs/pii/S004727272200175X