When Welby Ings was a social studies teacher required to teach kids about prejudice, he threw out all the resources about Polish Jews and American blacks and set up a real-life experiment.
It was at Hamilton's Fairfield Intermediate in the early 1980s. The term "nerd" was newly popular, and Ings and his students arranged to come to school dressed as nerds.
"We were going to be outcasts in our own school culture, and to celebrate we would have a bad-taste party together, with green cakes and purple ginger beer," he writes in his new book, Disobedient Teaching.
The 11-year-olds came dressed in pink socks with sandals, underpants worn over jeans, bow ties and running shorts and green hair.
But they didn't get a party. Instead, Ings took them in to Victoria St and asked them to walk 2km down the main street, one at a time starting at two-minute intervals, stopping at a shop to buy something on the way.
They were horrified. As he walked through town, the boy with underpants over his jeans was stared at and called a wanker and told to "f--- off" when he stopped to buy a Moro bar.
One girl wrote afterwards that when she changed back into ordinary clothes and looked at her nerdy costume, "it made me think of a skin, the sort of thing that other people can't take off".
She thought of a girl at the school with a cleft lip, who pulled her hood down over her face and spent her lunchtimes reading over by the basketball courts, alone.
For the first time, the girl in the nerd costume had an inkling of what life was like for the cleft lip girl.
"I thought of how I pulled my hat down over my face," the nerd girl wrote. "If that's what it's like for me, for ten minutes, what must it be like for her, for her whole life?"
Ings, now a design professor at AUT University, believes that transformative learning has to be emotional as well as intellectual. It certainly doesn't come from learning facts about Polish Jews or American blacks just to pass an exam.
He believes, conventionally, that schooling's purpose should be "that every individual is able to reach their highest level of excellence".
But he believes the best judge of success is not marks in an exam but the student's own judgment of whether they are achieving what they want from life.
With another class at Fairfield, Ings asked 12-year-olds to write letters to themselves aged 21, containing "their predictions and the goals they hoped to achieve".
Then he buried their letters at his parents' farm near Te Awamutu. He took them with him to Taihape College, where he kept them in the woodshed, and then up to Auckland where he taught at what was then Seddon High School (now Western Springs College).
When the time came to open them, he tracked down every student, by then living in Sweden and Israel, in flats and hospitals and in a house truck in Fiordland.
"I have never seen kids take that much care about what they wrote," he said.
"The fundamental thing at the base is belief. If a child loses belief in their ability to learn, you have lost them, and often as teachers their biggest job is to try and help a child recover that belief.
"That is why I have come to the belief that learning is both cognitive and emotional, because if you don't have belief, you can't learn."
• Disobedient Teaching by Welby Ings, Otago University Press, $35.