The price tag suggests the shirt is a snip at pound;9.99. However, when you reach the till, the shop assistant breaks the bad news: the shirt has been "mispriced" and actually costs pound;29.99. Time to stand up for your rights. But what are they?
Year 10 students are discovering the answer by taking part in Talkingshop (stand D66), an online role-playing session designed to inform young people of their rights as consumers. The teenagers assume a behind-the-counter role, acting as customer services staff in a busy supermarket, where they field questions and complaints from the queue.
Their collaborators in the exercise are genuine experts in consumer small print. Talkingshop was developed by Warwickshire County Council Trading Standards Service, and trading standards officers work online to offer help.
A typical session takes an hour, slotting into the Year 10 citizenship curriculum. Mark Ryder, national project manager for Talkingshop, says:
"Most schools only have time to devote one session to consumer rights.
Talkingshop allows teachers to run the session without having to become experts in consumer education."
The Talkingshop store sells food and drink, clothes, electrical items, lottery tickets and tobacco. Pupils work in pairs, responding to customer queries which arrive as online messages. There are helpful links to the resources on the Talkingshop website, which lay out the law, best practice and the supermarket's company policy.
From compensation to cooling-off periods, credit agreements to counterfeit goods, it is all here. If students become bogged down they can send an SOS to head office and a trading standards officer will help.
One task is to deal with a customer who bought a DVD from the store's online division, but has had a change of heart and is demanding a refund. "You have more rights if you buy online," says Mark. "You have a seven-day cooling-off period when you can return the goods, whether or not they are faulty."
The sad news about the shirt is that the shop is under no obligation to sell it for pound;9.99. Mark says: "By working behind the counter, students see things from both sides - there are consumer rights, but there are also obligations and responsibilities involved in being a trader. They also learn how to complain effectively, being assertive but polite.
Around 90 per cent of pupils who have taken part say they now feel more able to take goods back if they have a problem. "We used to visit schools, but it was very difficult to engage a class of 30. In Talkingshop, students get individual attention and get really involved."
Talkingshop is free and is in use in 14 local authorities around the country. Authorities buy into the scheme, fielding their own trading standards staff to collaborate with local schools. Mark says: "Here we can meet more schools and link up with local trading standards colleagues.
"We see a lot of people in their early 20s who come to us with problems.
Some are very vulnerable and not well off. They don't have a clue about their rights," he says.
"We want to get some basic messages across, and show young people that the law is there to protect them."
* Talkingshop Stand D66