As you read this, our teachers’ unions are preparing for war. For the first time in history they are planning meetings of 60,000 teachers, nationwide, during school hours.

Their target for this unprecedented action is unexpected. It is not an attack on their remuneration. Nor on their terms and conditions. Nor even changes to the national curriculum.

Instead, it is the indisputably well-intentioned Education Funding Review, which aims to solve the shortcomings in the school decile mechanism for funding schools.

The problems with the decile mechanism are widely recognised. It does not accurately target resources to children most at risk of underachievement. And it has unintended impacts by stigmatizing low-decile schools.

The review proposes replacing the decile mechanism with a standard per-child funding amount, with an additional funding amount for children most at risk of educational under-achievement.

The review also recommends schools be given a global budget covering salary costs and other operational costs of running a school. While the Ministry will continue to pay teachers’ salaries, salary costs will be a credit against a school’s global budget.

Both changes bring advantages. The per-student funding will more directly target at-risk children than the decile system. And global funding will increase flexibility for schools – in much the same way as bulk funding did in the 1990s.

Unfortunately, our teachers’ unions dislike change. If anyone can find a solution, they can be relied on to find a problem.

This time their problem is that global funding will allow schools to make trade-offs between salary costs and the other, non-teaching, costs of running a school. This, they say, could lead to increases in classroom sizes and cuts to teacher numbers.

But if schools gain the flexibility to improve educational outcomes by changing how they allocate resources, surely that is a good thing? Why should a school be prohibited from trading-off salary costs for, say, increased use of technology? That is exactly the trade-off that occurs in every other profession, every day. Why should schools be different? If there’s a better way, let’s free up our schools to find it.

The unions may claim to be guardians of our schools, but their protestations reveal something else. Their opposition has less to do with the interests of children than protecting their members’ jobs. We should not blame them for this. They are unions.

But let’s not mistake self-interest for the public interest – or the interests of those children most at risk. They deserve better.