For Labour, size matters. Particularly when it comes to education.
Among a plethora of promises made by David Cunliffe this week was a commitment to cut teacher-student ratios in primary schools from 1:29 to 1:26 and to reduce the average class size in secondary schools to 23.
This is a key point of difference with the National Government, which says it would rather spend more money on better teachers and principals than more teachers across the board.
Old-timers will often talk of going to school where grim sole-charge teachers ruled classes of 50-plus with absolute authority, but parental expectations of education have changed.
Back in the day, if you left school knowing how to read, write and do basic multiplication, your school days were deemed to have been successful.
If you were dyslexic, left-handed or learned in a different way, you were, it seems from the stories, deemed stupid and unteachable and left behind.
My mum, as a young teacher with only a couple of years in the classroom under her belt, was given a class of 52 new entrants in the early 1960s. She says the clever ones took care of themselves while she tried to shore up the gaps in the knowledge of those who hadn't had the advantage of early-childhood education.
She did her best, but she says it wasn't a great experience for her or for some of the kids.
Obviously, we wouldn't want to see a return to the days of classes that size, but will reducing the teacher-student ratio from 29 to 26 make that much difference?
I would rather my child be taught alongside 35 other kids by a brilliant, inspirational teacher than have her in a class of 15 with a boring dullard who is marking time until retirement.
And as new schools are adopting an open plan, learning hub, multi-teacher environment over the traditional one teacher, one classroom, one class approach, the teacher-student ratio becomes far less important than the class size.
Most children are doing just fine in our schools. They have parents who are engaged with them and their learning, who are willing and able to pay for extra tuition where it's needed and these children do well at any school they attend.
It's the very bright kids and those with specific learning difficulties who miss out when teachers are stretched.
I find it appalling that young people can arrive at secondary school incapable of reading the most basic texts and unable to write a simple essay.
Their parents have failed them, and so have their teachers.
Back in the days of the old-timers, kids were held back until their teachers deemed them fit to move up a class.
Although that's no longer considered appropriate, it seems a gross dereliction of duty that successive teachers will kick kids upstairs so they become somebody else's problem.
Teachers say they don't have enough time or resources to help those children — that only kids with the most severe learning difficulties get the aid available.
But that's a cop-out. Teachers have a powerful union and they can make a strong and emotive case for more teacher aides and specialist assistance for those children being let down by the system.
If teachers can promise me that smaller class sizes will ensure no child is left behind, I'm all for it.
But National is telling us that rewarding quality teachers and sharing them around schools will be more effective in lifting those children languishing at the bottom of the class.
Two different ideologies, two different ways of running schools. And our children are the lab rats on which these are being tested.
• Kerre McIvor is on Newstalk ZB, Monday-Thursday, 8pm-midnight.