Why do boys do better at math?

People differ in their mathematical ability. We all know this. Some of us suffered through high school math classes; others excelled. When looking at the overall distribution of scores on standardized math tests, a curious fact emerges: male students, on average, score higher than female students. Of course, individual females can have very high scores, and some males may have low scores, but overall the top of the distribution is more populated by males than females.
This raises an important question. Is the difference in math scores due to sex, or are we seeing an effect of social gender expectations?

A recent study in the journal Nature gives us part of the answer. Researchers examined math ability among French Grade One and Two students, offering intriguing evidence that biology is not the primary factor in math differences. The team, led by Pauline Martinot, looked at scores for more than 2,600,000 children taking standardized math tests at the start of Grade One in September, four months later in January, and at the beginning of Grade Two. France gives well-designed math and language tests to all students at these three times. All schools (private, public, Montessori or religious) at all socioeconomic levels are involved. Students enter Grade One in the year they turn six. Thus, children varied by as much as 12 months in age (a significant range), and some students in Grade Two were only a few days older than children starting in Grade One. The large size of the testing meant that differences could be looked at in a reasonably large sample.

The school effect

The authors’ findings are fascinating. At the start of Grade One, there were no differences in the distribution of male and female math scores. On average, older children did better than younger children among both males and females. But four months (and one year) later, male scores were significantly higher than the female distribution. This difference cannot be due to an aging effect because the scores of older children at the beginning of Grade One were similar in males and females. It appears that, for some reason, across all schools in France, by four months into school, boys on average scored higher than girls. The effect of being in school in some way is responsible for this difference. As many other studies show, this unsettling difference is maintained as education continues into university.

While this study demonstrates that differences in math ability are very unlikely to be due to the sex of the children, it is unable to determine the actual cause. Interestingly, at the beginning of Grade One, girls had on average better language skills than males, but this difference got smaller over the year, not bigger. What causes these differences is the subject of other studies, and I will suggest some possibilities next month.