Every three years, the OECD's Program for International Student Assessment (PISA) tests 15-year-olds on their problem-solving skills across literacy, numeracy and science, and on Tuesday night the latest results from 2018 were released.

After years of decline across all disciplines, Australia has reached a worrying new milestone - for the first time maths results have plunged to the international average.

Compared to the world's top performing countries, Australian students are now up to 18 months behind in reading, three years behind in science and almost four years behind in maths. They still achieve similar scores to those in Germany and the US, but trail behind the UK and New Zealand, while students in China and Singapore claimed top spots in the rankings.

Sue Thomson of the Australian Council for Educational Research, which manages Australia's PISA testing regime, said the result was a huge "wake up call" for Australia. Students are about a year behind where they were when testing began at the start of the millennium, having been overtaken by 14 participating countries.

Finland, long renowned for its education system, has also been plummeting down the rankings in recent years, particularly in maths, though it remains among the top performers overall.

"But I'm not seeing any other downward trends like ours," Dr Thomson said. "People say Australia is the new Finland, but not for a good reason."

Federal Education Minister Dan Tehan agreed the "very disappointing" results should ring alarm bells, calling for a de-cluttering of the curriculum in favour of the basics - literacy and numeracy. A meeting next week of state and territory ministers offered a chance to reset the national education agenda, he said.

"And we must be bold in doing so," Mr Tehan said. "Our students should be ranked among the best in the world."

On the raw figures, the ACT again topped the nation, even recording an uptick in results, particularly in reading, compared to the previous round of testing. But the capital was also among those jurisdictions singled out for long-term decline in maths scores.

Victoria recorded the smallest drop overall since testing in the discipline began in 2003 as well as stable results in reading and science along with the Northern Territory.

Dr Thomson said it was worth examining what Victoria was doing right, as well as results in the ACT, where student scores often drop considerably once compared with their interstate peers of similar socioeconomic advantage.

But the ACT government has resisted calls for a review of school performance, amid system-level audits interstate and a recent assembly inquiry into ACT test scores.

Education Minister Yvette Berry said the capital's new 10-year education strategy was built on extensive consultation and already reshaping classrooms as it ramped up both teaching training and student learning data and looked to address inequality between schools. An early years literacy program had recorded an 83 per cent improvement in participating schools, she said.

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Dr Thomson said Australia could learn a thing or two from countries on the rise like Portugal. The small European country has rocketed up the rankings since it launched dramatic education reforms in the face of poor results early on.

Australian students also record higher rates of bullying, stress and competition than the international average, and the socioeconomic gap in performance remains about three years.

While advantaged schools are less understaffed than others around the world, 34 per cent of Australian students at disadvantaged schools have seen their learning impacted by staff and resourcing shortages.

But Mr Tehan argued funding was not the problem, pointing to the high performance of countries like Estonia which he said spent half as much on education as Australia. While Dr Thomson agreed people were focused on improving schools, she said the distribution of funds between the public and private sectors needed a further look as Gonski's needs-based formula was rolled-out.

"We're not educating one group of students to the same extent as others, and we will pay for it in the long run," Dr Thomson said. "As society gets more technological, we have fewer and fewer jobs for people with low level skills."

But Dr Thomson admitted diagnosing the problem of Australia's failing results was difficult - possible culprits ranged from an increasingly crowded curriculum to growing shortages of trained maths teachers.

"There's no silver bullet, and we don't want to see a knee jerk reaction but this is the point that we need a big rethink," she said. "We've hit the average, next time we'll be below. The OECD has a wide range [of nations] in it, we're a wealthy first-world country, we should aspire to more."

She said it was time to review the entire system - from school funding and teacher training to the senior years' ATAR system - recently under fire, along with the controversial NAPLAN testing regime, for putting too much pressure on students.

While the "Asian powerhouses" now regularly topped education rankings, they could also see poorer student well-being, Dr Thomson noted.

"We need to look at the whole picture but we should be able to have happy students and good scores. This is about more than tests. This is how we prepare students."

More than 600,000 students across 79 countries took part in the 2018 round of PISA testing, including 14,273 Australian teens - 841 of whom live in the ACT. Australian results are sliding across both the government and private school sectors and in all disciplines, though reading is a little steadier.

In maths, the gender gap that closed in 2015 has reopened again in favour of boys.

Federal Labor spokeswoman Tanya Pliberseck described Australia's deteriorating results as "alarming" and called on the Coalition government to act.

On Tuesday, Mr Tehan flagged renewed pressure on his state counterparts to implement the national school reform agreement, urging them to "leave the teachers' union talking points at home". In particular, he pointed to learning progressions and better formative assessments - a key recommendation of the Gonski review - as well as phonics training for teachers.

But much of the education council's recent debate has focused on NAPLAN, as pressure to scrap it from the union and others in the sector mounts. Mr Tehan has backed the assessment as an important annual tool to measure the system's performance, after Victoria, NSW, Queensland and the ACT broke ranks to launch their own review into the test.