This week, the results of the ninth round of the OECD’s Programme for International Student Assessment (PISA) were released.

PISA enables countries to track their educational performance over time. Since testing began in 2000, PISA has measured fifteen-year-olds’ performance in science, mathematics and reading. New Zealand’s results have declined substantially in all three subjects over those 25 years.

The 2025 data are not earth-shattering. No one PISA round ever is. It is the long-term trends that matter. Still, New Zealand’s results bring both hopeful news and reason for ongoing concern.

The best news is that the gap between students from advantaged and disadvantaged socioeconomic backgrounds has reduced markedly since 2022. This also happened in some other countries, but only because the performance of their most advantaged students fell. In New Zealand, the gap narrowed because the most disadvantaged students improved.

New Zealand showed a five-point improvement in science since 2022. For context, the OECD treats a twenty-point gain as representing a year of educational progress.

So, the science improvement represents about a quarter of a year’s learning. It is the first increase New Zealand has shown on any PISA scale since 2009.

Mathematics improved by just one point, too small a change to count as meaningful. Even so, the result is encouraging. New Zealand’s decline has been steeper in mathematics than in science or reading and, until now, New Zealand’s mathematics achievement has declined in every PISA round.

The total decline has been 43 points – equivalent to two full years of schooling by the OECD’s metric. While little can be made of the single point increase, New Zealand may at least have bottomed out. Moreover, New Zealand’s steady result cut against a nine-point drop in the international average.

Offsetting the improvement in science and stabilisation in mathematics was a decline of four points in reading.

This result may seem perplexing. Education Minister Erica Stanford mandated primary schools to teach reading using internationally proven methods from 2025. But education policy changes usually take years to show up in test results.  

It takes time to bed in changes to teaching practice, especially in a highly devolved school system like New Zealand’s. Students starting school under these reforms will not participate in PISA until the 2037 round.

PISA 2025 shows some green shoots for New Zealand education. But for flowers to bloom, successive governments must stay the course with Stanford’s reforms.