Lesley Longstone, the secretary and chief executive of the Ministry of Education, says New Zealand cannot claim to possess a world-class education system. Strangely, Hekia Parata, Minister of Education said the very opposite just last week.

Ironically, both used the same facts to reach a different conclusion. So how do we define ‘world class’?

Is an education system ‘world class’ because it produces the best and the brightest? Or is it because it ensures a minimal achievement gap between the top and bottom students?

New Zealand’s top students are among the highest achievers in the OECD in literacy, science and numeracy.

Plus, on average, our students' achievements outrank those of students in most other OECD nations.

But an average is simply an aggregation – it does not explain the performance of the students at the tail end. New Zealand’s top students’ achievements mask the large gap between the highest and lowest performers.

In fact, New Zealand does have a high performing education system until you reflect on the stubborn characteristics of the tail end. The underperforming 20% of students are not all necessarily less academically able or lazy. They are, however, consistently from low socioeconomic backgrounds, from rural and remote areas, and of Mâori and Pasifika descent. It is an unfortunately familiar pattern.

The education system is not a failure per se, considering the results achieved for the majority of kiwi kids; however, for whatever reason it doesn’t cater for the bottom 20%. And a system that doesn’t work for 20% of students is one that needs improving.

Paradoxically, Ms Longstone and Ms Parata are both correct. New Zealand’s education system is simultaneously world class for 80% of students and inadequate for the bottom 20%. Educators should be proud of the system’s successes but also want a better one.

What improvements would make our education system better poses a bigger conundrum than an argument over the proper use of the term ‘world class’.