It took eighteen years for New Zealand’s school system to plunge from world-leading to decidedly average.

Despite a concurrent 32% real rise in per-pupil spending, in maths, Kiwi 15-year-olds now perform the way 13 and a half year-olds did just 20 years ago. In reading, Year 5s now rank 24 out of 26 participating OECD countries.

More damning, educational inequity is worse here than in Canada, Australia, the US and UK. And yet, over the same period, NCEA pass rates have rocketed up. Why the disparity?

The reason NCEA masks this basic dumbing-down is that, just like the curriculum, it is child-centred to the extreme.

On the face of it, child-centred schooling is wonderful – like ferns and chocolate afghans. However, it has been applied so uncritically in New Zealand that many teachers now believe they are at their best when students lead. They are convinced that whole-class teaching is old-fashioned and crushes creativity.

It is quasi-religious adherence to child-centred ideas that explains the open-plan classrooms, the rise of “independent” learning, collaborative projects and beanbags.

And paradoxical as it may sound, these approaches confuse the ends of education for the most effective means.

Consider the All Blacks. In preparation to face their opponents, these world-leading athletes do not spend most of their time practising rugby games. Instead, they spend most of their time memorising the broken-down parts of what makes them great on the day. They spend hours lifting weights, passing and kicking, practising strategy and set-plays. For them there are no shortcuts. Memorising every component is essential to expertise.

By comparison, the national curriculum side-lines knowledge in favour of competencies. For example, the entire curriculum for social sciences (covering social studies, geography, history, economics, etc.) for primary and secondary schools fits on one A4 page. Teachers can make all the choices. There is no content progression or accountability.

Fortunately, some schools still ignore child-centred orthodoxy. They find engaging ways to teach subject knowledge and expect their teachers to lead. However, many do not. Schooling has become a high-stakes lottery.

In this election, neither major party has come close to identifying the root cause of the school system’s embarrassing failures. That’s why my report ‘New Zealand’s Education Delusion: How bad ideas ruined a once world-leading school system’ uses evidence to point the way.