Girls who attend all-girls schools perform better on exams than girls with identical records and backgrounds in mixed schools, and they outperform boys at all-boys schools, according to research.

While girls' schools have long been recognized to outperform other types of schools in England, FFT Datalab's analysis discovered that even after controlling for background characteristics, there was an unexplained increase for kids at girls' schools, equivalent to 10% higher GCSE marks in 2023.

In contrast, boys at all-boys schools received no exam advantage over their classmates at mixed schools.

Although students who attend single-sex schools have better GCSE scores than the national average, most of this disappears when we compare the outcomes of single-sex students to similar students attending similar mixed schools, according to Dave Thomson, chief statistician at FFT.

However, FFT discovered that, when compared to mixed state schools, girls' schools continued to see a "modest boost" that could not be explained by the students' past academic performance or the lower percentage of students receiving free school meals or special needs.

According to Thomson, the “very slight difference” for girls’ schools equated to a tenth of a grade gain at the GCSE in each subject.

The head of the non-selective all-girls St. Marylebone CofE school in London, Kat Pugh, stated: "I believe that the reason why girls do better in single-sex schools is that the all-girls environment fosters an environment where girls can feel proud of their academic accomplishments and support one another's successes."

According to Pugh, one reason for the performance gap between boys' and girls' schools could be that females were adept at copying the strategies and behaviors of their successful classmates.

It has been shown that GCSE achievement can be attained through meticulous individual study practices such as creating mental maps, revising essays, creating flash cards, and working through practice papers. According to Pugh, guys in an all-boys setting cannot emulate successful learning practices if they are not exposed to them.

The results, according to Donna Stevens, chief executive of the Girls' Schools Association, which advocates for state and private girls' schools in the UK, supported earlier studies that found girls performed better in academic subjects like math, science, and computing when they were raised in a supportive environment that included reading more works by female authors.

Boys normally take up more of a teacher's time in a classroom, as evidenced by data; thus, Stevens suggested that removing boys from the picture would give the girls more teacher time, which would benefit their academic performance.

Stevens stated that although guys tend to be more "outwardly confident," hearing this all the time in a school setting might have a negative impact on a girl's confidence and self-belief.

According to the FFT analysis, the high percentage of selective grammar schools—54 out of 147 boys' schools—that make up England's 352 state single-sex schools accounts for a major amount of the schools' superior academic performance.

However, when compared to mixed state schools, even non-selective single-sex schools had fewer students from underprivileged families or with special educational needs. Additionally, single-sex schools are more common in wealthy regions of the nation; in London, nearly 25% of students attended a single-sex school, compared to just 3% in the northeast of England.

Although they and related factors explained 90% of the higher test results attained by girls' schools and left the remaining 10% unaccounted for, they did not account for the better exam outcomes received by boys' schools.

Our continued argument is that girls should be allowed the freedom to reach their full potential and make educated decisions about their interests, subjects, and careers. This is according to Cheryl Giovannoni, chief executive of the Girls' Day School Trust, which oversees 24 independent and state schools in England.