As an alumna of all-girl schools, I can tell you that the idea that girls in single-gender learning institutions are focused, charming little angels who never behave badly is laughably silly. (I'd like to formally apologize to all my teachers.) But single-gender education versus co-ed schooling has attracted a lot of attention, with parents wondering if it's better to have boys and girls in school together, or with their own gender. A new study from scientists at Utrecht University, published in the journal School Effectiveness & School Education, has shed new light on the argument — and their discoveries indicate that boys benefit educationally from having girls around. But does the practice of going co-ed help girls, too? The evidence on that side is a lot less clear.
The Utrecht study looked at 281,095 students from 10,425 co-ed schools who'd answered a 2009 survey called PISA (the Program for International Student Assessment), a global education study held by the OECD, or Organization for Economic Cooperation & Development, one of the biggest global economic organizations on the planet. The PISA asks 15-year-olds around the world in 33 of the OECD's member countries various questions about their academic performance, study environment, families and other questions. So this is a pretty global look at the state of co-education and how it affects learning, and the results show that, for boys at least, it's a good idea to have more girls around.
In schools with more than 60 percent girls, boys saw better reading scores if they were at a school with that ratio. The Utrecht scientists were controlling for a bunch of variables, from school resources to race to the education of parents and teachers, and the results were only really explained by one thing: more girls. Boys were far worse at reading if they were in a school with under 60 percent girls.
"Boys particularly seemed to be positively affected by a high proportion of female students in a school," the scientists wrote — and added that this isn't actually a new discovery. A 2004 study found that having girls around shifted the study cultures of schools, encouraging better habits in boys. "Girls possibly set a more successful learning climate in the schools and classrooms, to which boys were more susceptible," the Utrecht study suggests. But do boys inspire better habits in girls?
The Utrecht data says that there actually doesn't seem to be much advantage for girls to be around boys in terms of academic performance. And that's backed up by other evidence. A study done in the UK in 2016 found that 16-year-old girls in same-sex state schools (what we in the U.S. call public schools, as opposed to private ones that require fees) did better in important high school exams than those at co-ed schools. And the effects remained the same once you took things like socioeconomic status or whether or not a school was selective. And a study in 2017 that looked at the final few years of Korean high schools as they shifted from single-gender to mixed gender found that the results weren't good for girls. As their classes shifted from 100 percent girls to about 50 percent girls, the performance of the Korean female high school students decreased, while the performance of the boys didn't really shift at all.
However, the idea that single-sex education is always better for girls isn't universally accepted. A meta-study by the American Psychological Association pulling together data from 184 studies worldwide in 2014 found that single-sex and co-ed schooling only offered "trivial" differences in academic performance. The results involved 1.6 million students from 21 nations aged from kindergarten to grade 12, so it's one of the most comprehensive studies of the issue ever done.
Part of the reason results might differ between studies? Gender stereotyping. A study from Switzerland in 2015 gives some insight into this. Giving high school aged girls single-sex education, they found, improved their performance in mathematics but not in languages, which, the researchers behind the study explain, is probably down to gender bias: with a class of only girls, mathematics teachers were more likely to focus on teaching equally, and girls were more likely to attribute their successes in math to their own effort rather than luck. This idea is boosted by a 2010 review of the science around the single-sex debate in Revue française de pédagogie, which looked at data from a variety of countries where single-sex schools are popular. "There appears to be very little consensus on whether single-sex education is advantageous to girls’ or boys’ academic achievement," the author, Professor Emer Smyth of the Economic & Social Research Institute, noted. "However, there does appear to be at least tentative evidence that attitudes to subject areas may become more gender-stereotyped in a coeducational setting." And that's going to harm girls who love math and science.
Overall, it's not entirely clear whether or not girls benefit from having boys around in academic environments, while boys seem to get some good out of having a majority-female learning institution. But don't buy the stereotype that being single-sex guarantees good behavior and high marks for all involved. The extremely long-suffering teachers of my high school would beg to differ.