Paul, Casper, and I are currently putting the finishing touches on the update of the first book on Urban Myths. But completing it is tough because, of course, new studies keep appearing. This includes this new study concerning gender bias among teachers. The researchers used data from the French ELFE cohort study and followed more than 7,000 children from kindergarten to the fourth grade. In total, this involved more than 23,000 observations. They examined how teachers assessed students’ language and mathematics levels and compared these assessments with objective performance tests. In addition, they included the students’ externalising behaviour, such as impulsivity, hyperactivity, difficulty concentrating, and so on.

The results are interesting, but also less useful for those seeking sensationalism. In language, teachers rate girls higher on average than boys with comparable performance. In mathematics, the opposite occurs: boys are rated slightly higher than girls who perform equally well objectively. The researchers, therefore, speak of a perceptual bias that appears to reinforce existing stereotypes.

But the most interesting part of the study may not even be about gender per se, but about behaviour. Students with more externalising behaviour were systematically rated lower, regardless of their actual performance. That sounds logical in a way. A student who is constantly distracted, reacts impulsively, or disrupts the lesson will likely also appear less competent. However, boys exhibit this behaviour more often than girls on average. As a result, part of the lower language rating for boys appears to be related to behaviour rather than gender alone.

In mathematics, however, a bias in favour of boys persists even after controlling for behaviour. That makes the pattern more complex than a simple “boys are more active” explanation.

It is also interesting when these differences emerge. In France, the average difference in mathematics performance between boys and girls begins approximately in the first year of primary school. Teachers’ perceptual bias also appears to intensify from that point on. The authors cautiously suggest that teachers may reinforce existing differences in their perceptions. At the same time, they themselves emphasise that some of these interaction effects become less robust in additional analyses.

The latter is important. The study is strong, but naturally not perfect. It involves a large longitudinal dataset, with preregistration and control for socio-economic factors. That makes the results interesting. But it remains an observational study. Moreover, the “objective” performance is not entirely independent of teachers, because they administered and scored some parts of the tests themselves. The authors naturally acknowledge this explicitly.

Even more importantly, this research is about perceptions, not directly about discrimination or unequal treatment. That distinction can quickly disappear in public discussions. A teacher may unconsciously hold certain expectations without consciously treating students differently. The authors themselves are remarkably cautious about this. They explicitly state that they do not know to what extent these perceptions actually influence performance, study choices, or grades later on.

Nevertheless, I find the study truly valuable. Not because it proves that education is “sexist,” but because it shows something that is actually very human: teachers never look at students completely detached from behaviour, expectations, and context. That probably applies not only to gender. Teachers perceived those who come across as calm, focused, and socially skilled as competent more quickly. Those who are more restless or impulsive may pay a price for it.

This study is no reason to point the finger at teachers. On the contrary. It primarily shows how difficult evaluation actually is. Especially in a classroom full of children, where behaviour, motivation, language skills, and performance are constantly intertwined.