Everyone agrees: We need to talk about how we fund our schools. Ranking schools in 10 decile bands according to the relative deprivation of their neighbourhoods is a very crude way to decide resourcing.
Up to half of the funding available to New Zealand's 2500 school principals is allocated according to the 2006 Census, and whether their pupils at the time lived in blocks of state houses or in leafy green neighbourhoods full of high-earning professionals.
Eight years later, when those children have long since left school, it seems absurd.
So, rightly enough, Education Minister Hekia Parata wants to talk about how we fund schools. The trouble is, Parata talks fast. She talks faster than her advisers can think. In her Herald on Sunday interview proposing to fund schools by pupil progress, she has left her education officials behind, she has left the teaching profession behind, and she has almost certainly left parents behind.
In racing ahead with the idea of school performance funding, she finds herself isolated, with neither the measurement tools to reliably compare pupils' progress nor the evidence to show it can work.
That may explain the aghast reaction from her office, which first said her comments were being misinterpreted, then resorted to the plaintive cry that she had been "ambushed".
Really, her advisers are unhappy because she has been caught out - caught out telling the truth.
She has revealed the Cabinet's firm conviction that freemarket ideology is as applicable to purchasing school education as it is to buying a BMW or a nice dinner at one of Simon Gault's restaurants.
At first blush, her proposal has an attractive simplicity. Why shouldn't we give more funding to schools that provide a better education, just as we would pay more to any producer, manufacturer or service provider who offers us a better product?
Here's the difference, though: Our children are not customers purchasing an education commodity from their schools. Our children are the commodity. They are the raw material we feed into the schooling system at age 5. They are hewn into shape by their teachers and come out the other end as the finest young men and women their teachers can make them.
Schools must do their best with the raw material we give them. Some schools get to work with healthy, well-nourished children from well-educated families; other schools must work with the children of the poor, of immi- grants who don't speak English, and children with special needs.
Teachers at those schools will do their best. Sometimes they will perform miracles. But they will struggle to get their pupils to the same levels as the schools in the leafy suburbs.
Hekia Parata, it seems, would have us reward those schools whose pupils progress further and faster. Presumably, she believes this would provide struggling, straggling schools with the cash incentive they need to catch up.
If so, she is wrong. In the US, George W. Bush tried much the same thing with No Child Left Behind, tying funding to year-on-year improvement in standardised tests. The policy served only to increase the gap between the top schools and the bottom ones, penalising children at the latter.
Yes, minister, decile funding is a blunt instrument.
But it is better we sharpen the instrument than drop needs-based funding entirely.