Government schools in Victoria and NSW introduced mandatory pants and shorts options for girls in 2018 and Queensland made them compulsory for girls the following year.

But some private schools are dragging their feet in making progressive uniform updates, advocates say.

ACT representative of Girls Uniform Agenda Amy Blain told ACM some high-fee private and independent schools valued appearance over ability and resisted neutral uniform options.

"The push back is about image," she said.

"A lot of private schools think that in order to present the right sort of image for the dollars that they are demanding, it's about looking smart. And for girls that appears to need to be skirts or dresses."

Independent Schools Australia CEO Carolyn Grantskalns told ACM that every Independent school made their own rules on uniforms according to the values of the school and the expectations of parents.

"In some independent schools, uniforms are compulsory and in others, they are not," she said.

In 2018 WA mother Krystina Myhre's campaign led to a government policy change to prevent female school students being limited to skirts and dresses.

Her daughter's public school had previously refused to allow her to wear shorts to school.

In Victoria, schools including Warrnambool College, Emmanuel College, Catholic Regional College in Caroline Springs, Tintern Grammar in Ringwood East and Cornish College are among the many schools that have expanded their uniform options.

University of Sydney school of education and social work senior lecturer Victoria Rawlings told ACM there were many reasons gender specific uniforms could be uncomfortable for young people.

"While many schools subscribe to the thinking that uniforms are equalisers through their masking of difference, when they are forced onto young people school uniforms can achieve the opposite of that intention," she said.

"Young people might feel alienated, misunderstood, unseen and devalued by being required to wear clothes that are at odds with their sense of self.

"Having gender neutral uniforms might allow students to choose combinations of clothing that feel more comfortable for them and indicate to the school community that difference is institutionally noticed and supported."

A 2020 Victoria University survey of 727 Australian girls found 88 per cent preferred to wear shorts during school sport and 65 per cent did not want to wear skirts during sport.

Queensland-based school uniform designer and manufacturer Mr Charles said there had been a significant uptick in gender neutral uniform design requests in the past five years.

"We were hearing that the girls were wearing boys shorts at school, so we started looking at a fit that would best suit females," Mr Charles' Rebecca Callinan told ACM.

"At the end of the day we just want our students happy and comfortable and it's really good to be able to have something in there that everybody is able to wear and feel comfortable in," she said.

Girls Uniform Agenda's Amy Blain told ACM rigid uniform policies at private schools involved regulation of young people's bodies.

"There's so much policing and control of girls. We know that that is still happening. Stories come in all the time about girls being required to kneel down to prove their skirt length," she said.

"This is not the best way to get kids to do their best learning and to perform their best, because they're being told constantly that they are going to be controlled, and that their appearance matters above everything else."

The Teach Us Consent movement, spearheaded by Australian activist Chanel Contos, has posted stories of Australian schoolgirls' experiences with rigid uniform policies, including accounts of having skirt and dress lengths measured by staff.

A study by the University of Wollongong in 2012 found girls deliberately sat out lunchtime games because they were worried about their skirts flying up.

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University of Sydney's Dr Rawlings said deterring girls from taking part in physical activity could have a big impact on education outcomes.

"The potential of seeing under skirts and associated teasing, for example, can prevent swinging on monkey bars, cartwheels, running easily, jumping or other vigorous exercise," she said.

"These garments prevent comfortable sitting on classroom floors in primary schools, decreasing concentration and engagement in class.

"These early impacts of uniforms on body movement have ongoing effects on girls through their schooling and are furthered in high school where girls are more commonly required to wear dresses and skirts."

ACT guidelines for equitable uniform policy advises schools to avoid using phrases such as "pants and shorts are available for girls if required" or "the preferred option for girls is a school dress" to prevent discrimination.