To promote this idea and raise the debate on the importance of cooking in the curriculum, the RSA is staging an event on May 13 called Cooking Counts.
Three masterchefs will teach 30 nine and 10-year-olds from a north London primary school how to cook supper for 200 guests.
"Everyone accepts there's a problem about teaching cooking and other practical subjects because they are too expensive. After-school clubs might be the way.
"I've given up on cooking in secondary schools. It was terrible years ago - all fat and sugar - it wasn't good cooking. So we don't want to go back to that. Food technology is not a bad course, but it doesn't make you a good cook."
Ms Leith said primary schools have more flexibility in their time tables and added: "I'm with the Jesuits - I want to get them young."
Children can learn maths through weighing and measuring, learn to shop economically, and chemistry - "by seeing how mayonnaise works, or the effect of lemon juice on condensed milk - and you have the pleasure of eating it".
Ms Leith would like the RSA to set up a research project to teach cooking in a primary school for an hour a week and track children's progress through secondary school to discover if they still practised it, if more boys than girls had stopped and to see whether it had helped them in other subjects.
She is also worried about the diet of children from poorer families. Getting enthusiastic about cooking early in life could help, she believes.
"When I was on the Channel 4's poverty commission it was a shock to find that eating was not a pleasure when you're poor. I underestimated how the other half lived. What worries me is that we're getting an increasingly divisive society. Teaching them to cook won't solve the poverty problem."
Britain should follow the French example by making gastronomy one of the arts as a way of stemming the tide of young people growing up with dulled tastebuds on a diet of hamburgers, she said.
The Primrose Hill children will be divided into three sets to work with the three chefs for 40 minutes each.
Caroline Waldegrave, principal of Leith's School of Food and Wine, will be in charge of spinach and ricotta filo pastry strudels and samosas; Anton Edelmann, head chef of the Savoy, will show them how to make tagliatelle with lamb balls and peppers; Albert Roux from Le Gavroche will make bread rolls and bread and butter pudding.
Mrs Kaushi Silva, head of the 470-pupil multi-racial school, said pupils baked cakes regularly to raise money for school funds, but cooking was usually supervised by volunteers, not part of the curriculum, although the children learned about healthy eating and nutrition in science lessons.
The RSA event proved so popular that the 30 children and four teachers taking part had to be picked from names out of a hat. Preparation for the day is being confined mainly to safety, she said.