On a sunny day, nothing is quite as delicious as an ice cream. But for two British couples visiting the Spanish Steps in Rome, Italy, a EUR64 (#163;54) bill for four of the treats seemed a lot to swallow.
Roger Bannister, his brother Steven and their respective wives, Wendy and Joyce, were astounded to be charged EUR16 each when they ordered four ice creams at the Antica Roma bar and gelateria.
"And when we paid up, they didn't even say thank you," Roger Bannister told the Corriere della Sera newspaper. "It's incredible. It can't be normal, can it?"
Would your students expect to pay more for a treat abroad? They could look at the price of ice creams in popular holiday destinations as a geography activity, or weigh up the differences as a route into addition and subtraction in mathematics.
Specialist ice-cream parlours and fashionable frozen-yogurt shops - a niche market that originated in the US - are popping up across the UK. And spending has increased: the British are forking out about #163;17 per person on ice cream each year. Still, other nations spend more: Norwegians spend NKr290 (#163;33) per head per year, Australians A$46 (#163;30) and the Swiss SFr37 (#163;25).
But the price people are willing to pay does depend on what they are buying, says Vince Mitchell, professor of consumer marketing at Cass Business School in London, England. "People won't pay (a premium on) it if everyone else has got it - you've got to have exclusivity," he told BBC News Magazine.
Perhaps this was why the British couples in Rome felt so cheated - eating gelato in Italy's capital is hardly an exclusive experience.
"You're not buying the ice cream, you're buying (the experience of) Rome," says Ronnie Ballantyne, lecturer in marketing at Glasgow Caledonian University in Scotland.
But was there something special about the flavours or ingredients of the ice cream in Rome? Ask your students to compare recipes and even make their own ice cream.
The earliest instance of anything like ice cream being served was in China during the Tang period (AD618-907), according to the UK Ice Cream Alliance. The first ice-cream machine, meanwhile, was developed in 1843, the alliance claims.
Mitchell says that the constant reinvention of the high and low ends of the ice-cream market means that "you can now have what you like". But you may be charged a lot more for it.
What is more important: where you eat an ice cream or what it tastes like?
Would you pay more to eat an ice cream in a wonderful place with your friends?
If you thought an ice cream was too expensive, would you complain? What would you say?
You have been charged #163;54 for four ice creams: how much did each one cost?