The teachers' strike is about maths. They're still OK with teaching it, they don't want it removed from the curriculum or anything, but teachers have been doing their sums, and they're not happy with the answers they've been coming up with.

No matter what you subtract from a weekly budget, a teachers' salary isn't adding up to a realistic chance of home ownership in our major cities. While high rents, especially in areas where our most affluent schools are located, is making it extremely difficult for principals to retain and attract good teachers.

Therefore the union representing primary and intermediate teachers wants a 16 per cent pay rise over two years. They hope this will make a difference to retention and reverse the fall in people wanting to become teachers. The Government isn't on the same page, offering 4 per cent over the same period.

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That's the money side of the equation, then there's workload. It's not the whole answer, but the workload pressures teachers are vocal about could be relieved by adjusting student to teacher ratios.

Currently the Ministry of Education funds one teacher per 29 students for Year 4 to 8. The teachers' strike demands include a new ratio of 1:25.

Having some experience with teaching, I can confirm what's common sense - smaller class sizes make a difference. In maths speak that's "inverse proportionality". Reduce class sizes, teaching quality and student achievement goes up.

Teachers also want special needs coordinators in every school. Fifteen per cent of students are identified as having special needs. Classroom teachers need help so that these students' needs are best met, and the teaching of other students in the classroom is not affected.

The list of teacher demands leads to an equation we all understand: more teachers + more pay = more Government funding.

This is where the teachers' maths comes into conflict with the Government's maths.

Thanks to Finance Minister Grant Robertson's tight hold of the money flow, government spending is on track to be around 33 per cent of GDP for 2018-19. GDP being the yearly economic output of a country measured in dollar terms.

Now in maths, it helps to understand the value of something by making comparisons. One of the first exercises in number learning is to arrange numbers in order from lowest to highest.

We could do that with a selection of countries to get an idea of how our government's spending compares: India (12.74), Albania (29.70), South Korea (32.26), New Zealand (33.70), Australia (36.20), United States (37.80), United Kingdom (41.40), Iceland (41.90), Germany (43.90), France (56.50).

Comparing New Zealand to countries we should be comparing ourselves to, reveals that we don't have a big taxing big spending government. It's a myth that needs to go the same way as meth house contamination.

If we were to increase government spending to the same percentage of GDP as Australia there would be more than enough money to meet the demands of teachers and fix the health system.

And before it's protested that the Government doesn't have the money, it could be found by introducing a new top tax rate for high earners, and by better taxing profits on rent, financial speculation and capitals gains. That's simple maths.

■ Vaughan Gunson is a writer and poet interested in social justice and big issues facing the planet.