A child without trainers is like a turtle without its shell, a budgie without its feathers. In the children's universe, trainers are more than shoes. They confer status more than any other single article of clothing.
But there are trainers and there are trainers. To be outside the acceptable half a dozen brands is to invite sneers and smirks.
So when Ellie comes to school with what are derisorily known as "market trainers," she walks in air-cushioned trepidation. It's a long time since she's had a new pair of shoes and she loves looking at the glaring whiteness of her new trainers. But she knows that they'll be mocked for not being the real thing.
How do you mitigate the effects of snobbery on the child whose family is poor? That old chestnut that it's in children's nature to be cruel may have a grain of truth, but it's also true that empathy can change attitudes.
But first things first. Find a private, uncontrived way of letting Ellie know that you think her new trainers are lovely. Do they make her feel like she's floating on air? Your niece has green air bubbles, too.
Then in a similarly quiet way, have a word with the teasers. As a teacher, you'll know that shaming and blaming will only alienate.
But offering different perspectives can illuminate a situation. If they came into school wearing something a bit different to everybody else, what response would they like to get? Does wearing clothes without particular labels make them a lesser person? Does having all the latest and most expensive gear make them cleverer, funnier, more attractive?
Pluck a story out of your repertoire of contemporary morality tales. With the social currency that having the right trainers carries with it, some children in our unequal society will inevitably suffer. But you can soften the stigma for the Ellies of your school through gentle but firm intervention.