A neighbour was telling me about the school uniform at a nearby co-ed public primary school.

“Yes – grey for boys and blue for girls.”

She caught my ‘are you serious?’ look and said, “yes, at some point a parent asked why they couldn’t all just wear the same shorts, and a member of staff replied, ‘but then how would we tell them apart?’”

Indeed, a fear of not being able to ‘tell them apart’ or ‘know the difference’ lies at the heart of many concerns about gender and schools today. Many Sydney schools, especially at the secondary level, cling steadfastly to gender segregation. Some recent reporting has shed light on parent frustrations in parts of Sydney where they have no co-ed public high school option.

The fear of not being able to tell boys and girls apart has a long and important history. It was especially prevalent in American Progressive Era scholars such as G Stanley Hall, president of Clark University, often dubbed the “father of adolescence.”

When psychologists and other experts first started writing about adolescence, they were also stressing the importance of something Hall called ‘differentiation.’ A changing economy meant a lot of men took up middle management jobs in which they no longer made things with their hands.

Their work, some feared, resembled the labour women performed. Hall and others saw schooling as a tremendous opportunity to differentiate what boys and girls learned in accordance with their rigidly divided roles they were to take up after school. Boys could learn woodshop, girls cooking, sewing, laundry, and other areas of “domestic science” in gender-differentiated classes.

Historian Gail Bederman has shown how these ideas of gender differentiation were closely linked to ideas of race, especially through notions of civilisation as defined against savagery. According to these late-19th and early 20th-century Progressive Era attitudes, one could separate the civilised and the savage by the degree of their sexual differentiation.

In so-called “savage” groups of people (ie. non-white), men and women could not be distinguished. Women carried heavy loads, performed hard labour, and showed aggression. Men were emotional, wore skirts, and failed to protect women. White middle-class ideas of separate (gendered) spheres therefore used differentiation as a means of asserting race. Middle-class Progressives made their not-to-be blurred versions of manhood and womanhood into signs of civilisation.

A browse through websites of several Sydney-area gender-segregated high schools reveals class offerings and descriptions of facilities that show the desire for differentiation is not merely a thing of the past.

Some schools offer sewing and “child studies”, while others boast about their two new wood shops and a metal shop with the latest power tools. We could remove all names and pronouns and still see plainly which websites described schools intended for which gendered category of child.

Indeed, while adjectives associated with manhood or womanhood may have shifted slightly, it is hard not to see these century-old notions of differentiation alive and well amid gendered high schools.

A large billboard advertising a private gendered school reads, “The [school name] school girl is fearless and brave.” Many boys’ high school websites boast they will produce “compassionate” men. I understand that the rhetoric is trying to overturn gendered stereotypes. The assumption seems to be that girls/boys might not be born (or socially conditioned) to be brave/compassionate, but if your daughter/son goes through this school she/he will become that.

Still, segregated schooling clings tenaciously to the project of making, proving, perpetuating, or advertising gender difference.

Whether advocates of gendered-segregated education make their case on the basis of biological essentialism or an essentialised social experience, both depend on and contribute to gender differentiation.

Some schools that refuse admission to girls will announce they know science says that boys “learn by doing” and “need to be heard”. Other school leaders who refuse entry to boys boast they will educate students to be “free-thinking” and “challenge community assumptions about the … limitations of women”.

One is left to wonder, what if daughters want to learn by doing and what if we want sons learning to oppose misogyny (or, even better, hearing from girls their age about sexism)?

If there’s no uniform, then students wear whatever coloured shorts they like. But if there’s a school uniform at a co-ed school, why can’t they all wear the same-coloured shorts?

Schools that exclude people on the basis of gender assert an exclusive identity that conforms to a middle-class, excruciatingly well-mannered, differentiated, and yes, “civilised” picture of womanhood and manhood one can easily “tell apart.”

And in the competitive marketplace that is secondary education here, these schools find it useful to brag about how they will teach a gendered category of kids a gendered idea or behaviour in a way that accommodates a gendered learning style.