Does gender-segregated schooling make a difference?

Expert opinion from University of Auckland - Waipapa Taumata Rau

Opinion: The debate over single gender versus co-educational schooling has long been controversial. I went to a co-ed school and was inspired by a remarkable woman who was my maths teacher, and because of her deep knowledge and passion for the subject, I knew that maths was definitely an option for girls – she was my role model.

It may well be that because of her, I went to uni and majored in maths – a path that led to a scholarship to complete a PhD in pure mathematics at Rice University in Houston, Texas. I loved my co-ed school – which is just as well as there was no alternative. Everyone went to co-ed schools in my hometown. Would it have made any difference if I’d gone to a single-gender school?

It came as a big surprise to me when I moved to New Zealand to realise that over 14 percent of secondary students attend single-gender schools. Moreover, unlike the USA and Australia, where single-gender schooling is predominantly offered by private and/or Catholic schools, most New Zealand gender-segregated schools are state schools. In many parts of New Zealand, students don’t have a choice – they are zoned only for single-gender schools. For a maths education researcher like me, New Zealand presented an exceptional opportunity to investigate the impact of gender segregation on maths education.

A few years ago, I was contacted by Distinguished Professor Geoff Chase from the University of Canterbury. He and his colleagues noted a strange statistic: of all girls enrolled in engineering degrees at the University of Canterbury between 2005 and 2017, 56 percent had attended girls-only schools. This is almost five times higher than expected.

Another report by the Ministry of Women found that girls from girls-only schools in Auckland ranked more male-dominated professions in their top 10 occupational choices than girls from co-educational schools in the same city. But the research into the impact of single-gender versus co-ed schools and whether it affects students’ interest and achievement in Stem subjects (Science, Engineering, Technology, and Mathematics) is complicated, and often contradictory. A comprehensive study of schools in Seoul in South Korea, where assignment to single-gender or co-ed high schools is random, found significantly positive effects of all-boys schools consistently across different Stem outcomes, but not for girls.

My summer research scholar, Alice Smith, and I decided to investigate the role of school type on the maths and science achievement of Year 9 girls and boys in New Zealand.

We examined data from more than 5,900 Year 9 students, sourced from the Trends in International Mathematics and Science Study (TIMSS) 2019 dataset. The findings of our study reveal a compelling narrative: students at girls-only and boys-only secondary schools did better at maths and science than their peers at co-ed schools.

However, the extent of this advantage and its significance depended on gender and the socio-economic background of the students. Boys at single-gender schools perform significantly better than in co-ed schools with small effect sizes across all socioeconomic bands, which is in line with international evidence. However, the results for girls were surprising.

The outperformance was most pronounced by students in low socio-economic environments. Girls at low-decile girls-only schools performed significantly better than their counterparts in co-ed schools, and the effect size was large. They also surpassed boys in both boys-only and co-ed schools with medium effect size.

In the high-decile band, however, the advantage of girls-only schools was insignificant.

What could explain these findings? We don’t know. We can speculate that single-gender schools may excel in counteracting prevailing gender stereotypes that have long plagued maths and science. We can speculate that by purposefully positioning themselves as bastions of gender equality, these schools create environments where aspirations aren’t circumscribed by gender norms. St Cuthbert’s College for Girls in Auckland is an example of a school that actively promotes the involvement of women in Stem fields through deliberate messaging and engagements with prominent female Stem leaders who serve as role models.

However, we must approach these findings with a critical lens. We need to be mindful of the potential confounding factors such as selection bias. It is plausible that academically inclined students gravitate towards single-gender schools, skewing the results. On the other hand, students in many New Zealand regions have no choice because of zoning since public single-gender schools are the only option.

Other study limitations are the lack of longitudinal data – we do not know what happens during all five years of secondary schooling and our study involved a small sample size of low-decile schools; only two low-decile girls-only schools were in the sample (versus 26 co-ed schools), raising the possibility that idiosyncratic factors had an effect and the results can’t be generalised.

But we clearly need to understand what those two low-decile girls-only schools did so well. Could the absence of boys in maths and science classes diminish the manifestation of societal stratification and remove the stereotyping effect – a well-documented phenomenon known as stereotype threat? What is more than apparent is that while we still have single-gender schools, the impact of that on students’ education and their career choices needs to be better understood.