I am in my classroom helping a group of students when I hear Andrew mutter contemptuously, "Bloody Muslims!"
I haul him out of the room. "I just want to check how much you know about Islamic culture," I say. "Can you tell me how the Arab world kept maths alive in the time between the Greeks and the Renaissance?"
He looks at me uncomprehendingly; I take this as a no.
"Or perhaps you can tell me about the wonderful tiling patterns you can find in many mosques."
Am I overdoing it, I wonder? I press on. "Andrew, do you call your Islamic friends 'bloody Muslims'?"
By now Andrew's head is bowed; he's got the message.
I like Norfolk, where I teach, enormously. But ethnic minorities make up only about 1 per cent of the county, which can mean that our students find other cultures a challenge.
Some people say that a world without religion would be a better one. I say that bad religion is indeed a grave problem, but that good religion is the bee's knees. Speak to a true Muslim, or a true Christian for that matter, and one cannot fail to be drawn to their faith. Purity, truth and justice are the obvious fruits of a life spent worshipping the Almighty.
But then... I remember reading six years ago about Mohammed Halim, a teacher in Afghanistan. In an article titled "Disembowelled, then torn apart: the price of daring to teach girls", The Independent described how "his life was over...his remains put on display as a warning to others against defying Taliban orders". Would Andrew find fuel for his prejudices here?
But then... I also remember asking a fellow student who was a Muslim why she had chosen the University of East Anglia for her studies. "Because it's safe," she said simply. The "Christian" West has its problems with violence, too.
When it comes to encouraging an awareness of the riches of Islam, I hope that I've demonstrated that mathematics teachers the world over are well placed to help: indeed, the word "algebra" was gifted to the world by a Muslim mathematician. So I would plead with the Taliban and politicians such as George W. Bush and Tony Blair - as well as with other Christians who are too ready to take us into conflict with Muslim countries - to make peacefulness a cornerstone of their faith. That would make it so much easier for teachers to oppose Islamophobia and Christianophobia wherever we find them.
Jonny Griffiths teaches maths at a sixth-form college
Show pupils how maths and Islam connect using mrsblacknell's pop-up three-dimensional nets and Islamic patterns lesson.
Or try tp_1986's lesson on Islamic art and symmetrical patterns.