Classmate Katie Beasley has tapped into Jubilee fever with her Union Jack cards. But just before the summer half term, 10-year-old Nimco Cabdi found that her Christmas cards weren't selling, so she branched out into polystyrene cups festooned with ribbons and silver paper to avoid bankruptcy.
It seems it's never too early to learn about economics. These pupils have created their own currency - "double troubles"-and written business plans, set up stalls and traded within a framework of laws, banks and civil servants to enable the society known as Double the Trouble to function. They've had talks from a bank manager, an MP, a policeman and members of the local business community.
The pupils, guided by teacher Pam Woodhouse, are part of a "microsociety", a citizenship-related idea that began in California. It equips upper juniors to handle issues of personal finance and business enterprise.
The idea is being used in other schools in the borough with help from the Merton Education and Business Partnership. Gillian Morris, its chief executive, is a microsociety enthusiast but says teachers need training and pupils need to be debriefed after each session to make sure trading rows don't spill into the playground.
We visit some Year 6 pupils who set up a microsociety - Tornado Town - last year. Ms Morris explains why most countries use paper money. Pupils agree that cows would be too big and apples would go off. Last year, this group of sparky 10 and 11-year-olds were trading in Tornadoes.
Charlotte Garrett and Charlotte Lui want to be designers. They started making and selling paper flowers, then moved into wax blooms and couldn't keep up with demand. The flowers didn't sell. "You've got to make sure people want what you're selling," says Charlotte Garratt - an early lesson in supply and demand.
The 12-week course is just the kind that Sir Howard is keen to see. Daniel Johnson and Charlie Tapping made a hefty profit on their Cool CDs and Terrific Tapes stall, raising prices as business flooded in, and reported a pupil with fake currency to the Tornado Town authority. They also had to budget for rental on the machinery.
Emma Coulson, 10, bank manager and entrepreneur, stresses the importance of planning. "You have to do a lot before you start up - like writing a business plan. And it's really important to keep your books up to date and pay tax. Otherwise you'll get fined." Gordon Brown would be proud of you, Emma.