Mathematics: Australia’s two-decade steady decline in proficiency

Australia’s latest PISA results confirm a long-running deterioration in school mathematics performance that can no longer be dismissed as a temporary setback.

The Programme for International Student Assessment (PISA), run by the OECD, tests the capabilities of 15-year-olds across participating countries. In mathematics, Australia’s score has now fallen at every single PISA cycle since 2003. The national average has declined from 524.3 in 2003 to 477.5 in 2025 — a fall of 46.7 points.

That is not just a bad year. It is a two-decade trend.

Importantly, this is not mainly a COVID story. By 2018, before the pandemic, Australia’s mathematics score had already fallen to 491.4, meaning most of the long-run deterioration had already occurred.

The result beneath the headline average is even more concerning. In 2003, Australia had 19.8 per cent of students performing at the top levels in mathematics, compared with 14.3 per cent classed as low performers. In other words, Australia had more top maths students than weak ones.

By 2025, that position had reversed dramatically. The share of low performers had risen to 29.1 per cent, while the share of top performers had fallen to 9.9 per cent. Australia now has almost three low-performing maths students for every top performer.

That is a profound change in the shape of educational performance. It suggests the problem is not confined to one small struggling cohort. Australia is producing fewer outstanding maths students while also seeing a growing share of students fail to reach basic proficiency.

There is, however, an important qualification. Australia is still above the OECD average in mathematics. In 2025, Australia scored 477.5, compared with an OECD average of 463.0.

But that should not provide much comfort. Using the OECD’s consistent comparison group, Australia’s lead has narrowed sharply. In 2003, Australia outperformed the OECD-23 average by 22.1 points. By 2025, that advantage had fallen to just 8.1 points.

So the real story is not that Australia has already become a poor performer by international standards. It is that Australia has experienced a clear and sustained decline, and its former margin of strength has been steadily eroded.

If this trend continues, the country’s future stock of numerate workers, professionals and high-skill problem-solvers will be weaker than the one that preceded it.