Girls who attend all-girls schools get better exam results than girls with similar records and backgrounds at mixed schools – and outdo boys at all-boys schools – according to research. While girls’ schools have long been known to outperform other types of school in England, the analysis by FFT Datalab found that even after adjusting for background characteristics there was an unexplained boost for pupils at girls’ schools, equivalent to 10% higher GCSE grades in 2023. In contrast, boys at all-boys schools received no exam boost compared with their peers at mixed schools. Dave Thomson, FFT’s chief statistician, said: “Although pupils who attend single-sex achieve better GCSE results than the national average, most of this disappears when we compare the results of pupils who attend single-sex schools to similar pupils attending similar mixed schools.” But FFT found a “modest boost” remained for girls’ schools that could not be attributed to their pupils’ prior academic records or the lower numbers on free school meals or with special needs compared with mixed state schools. Thomson said the “very slight difference” for girls’ schools was equivalent to a tenth of a grade improvement in each subject at GCSE. Kat Pugh, the headteacher of the St Marylebone CofE school, a non-selective all-girls school in London, said: “My hunch as to why girls perform better in single-sex schools is that being all-girls facilitates a culture of achievement and a sorority in which girls celebrate and enable each other’s achievements and can feel proud of doing well academically without inhibition.” Pugh said one possible explanation for the difference in performance between boys’ and girls’ schools was that girls were very good at emulating their successful schoolmates and the techniques they used. “Careful independent learning habits like making mind-maps, practising essays, making flash cards, working through practice papers, are demonstrably effective for GCSE success. If boys in an all-boys environment aren’t seeing the learning habits which lead to success, they can’t copy them,” Pugh said. Donna Stevens, the chief executive of the Girls’ Schools Association, which represents UK state and independent girls’ schools, said the findings backed previous research that suggested girls flourished in an environment geared towards them, including studying more female authors, and were more likely to succeed in subjects such as maths, sciences and computing. “We know, and research shows, that boys typically in a classroom take up more of a teacher’s time, so if you remove boys from the equation the girls are going to have more teacher time, and that’s going to be helpful in terms of achievement,” Stevens said. With boys being more “outwardly confident”, Stevens said that for some girls, “if you are hearing that all the time in a classroom environment, it does start to affect your belief in yourself and your confidence”. The FFT analysis found that the superior academic performance of England’s 352 state single-sex schools could largely be explained by the high proportion of selective grammar schools, including 54 out of 147 boys’ schools. But even non-selective single-sex schools had fewer pupils from disadvantaged backgrounds or with special educational needs compared with mixed state schools. Single-sex schools also tend to be concentrated in wealthier parts of the country: nearly a quarter of pupils in London attended a single-sex school, while only 3% in the north-east of England did so. While those and similar causes accounted for the better exam results enjoyed by boys’ schools, they only accounted for 90% of the higher results achieved by girls’ schools – leaving 10% unexplained. Cheryl Giovannoni, the chief executive of the Girls’ Day School Trust, which runs 24 independent and state schools in England, said: “We continue to argue that the real value is added when girls are given the space they deserve to develop their full potential, and to make informed and unconstrained choices about interests, subjects and careers.”