Fifteen-year-olds in the ACT are performing worse in science, maths and reading compared to 20 years ago, new international assessment results show.
The latest results from the 2022 Programme for International Student Assessment show the territory came out on top for all domains on mean scores compared to other Australian states.
However, when socio-economic advantage is taken into account, the ACT did not perform as well across the key domains and a large portion of students are still not meeting basic benchmarks.
In mathematical literacy, just over half (57 per cent) of ACT students met the national proficient standard but when testing began in 2003, three quarters of students were reaching this benchmark.
Between 2003 and 2022, ACT's mathematics scores declined 50 points.
In mathematics, the share of low-performing students has doubled to 20 per cent and the proportion of high-performing students has halved to 13 per cent in this time period.
In reading literacy, 66 per cent of ACT's students were meeting the national proficient standard, compared to 58 per cent across Australia.
Since 2000, the ACT's reading results are down 35 points and the number of high performers was down 10 percentage points and the number of low performers increased by eight points.
The ACT had 66 per cent of its students reaching the national benchmark for scientific literacy, but the mean scores had also declined 26 points since 2006.
The ACT is the most advantaged jurisdiction in Australia, with only 13 per cent considered disadvantaged and 38 per cent considered advantaged.
Centre for Independent Studies education research fellow Trisha Jha said when looking at mean scores adjusted for educational advantage, the ACT was behind other states.
The adjusted mean score for mathematics was 470, which put it 12 points behind Western Australia and four points behind NSW.
"You really need to understand that once you adjust for the ACT's level of socio-educational advantage, these educational advantages or the educational or high performance of the ACT really starts to melt away," Ms Jha said.
Ms Jha said the results reinforced the need to have a thorough review of the ACT's performance and practices when it comes to literacy and numeracy.
"It also shows that the conversation needs to move beyond simplistic high-level discussions around 'how much money do schools get' and things like that, because we know that schools are fully-funded. We need to focus on the guts of what teaching and learning actually is, what is going on in the classroom," she said.
"We know that things like really rich and well sequenced curriculum and explicit teaching are effective for all students, particularly those from disadvantaged backgrounds. And we need to understand fully to what extent those practices are reflected in ACT classrooms."
In all domains when student-level socioeconomic background was accounted for independent schools performed better than Catholic and government schools.
Australian Council for Education Research senior research fellow and report co-author Lisa De Bortoli said it was encouraging to see Australia's result stabilise, but our position in the top 10 countries was largely due to the performance of other countries dropping.
"Just over half of Australian students achieved the National Proficient Standard - 51 per cent in maths, 58 per cent in science and 57 per cent in reading - so a significant number of students are failing to demonstrate they have more than basic skills in those areas," Ms Bortoli said.
"The fact that Australia's performance is largely unchanged since 2015 may be good news in the context of the 2022 results, but it's not the time for complacency."
