The teachers in charge had a portable TV on a table by the finishing line, and fell silent as they saw an elderly gentleman, Jacques Rogge, International Olympic Committee president fumbling with an envelope.
Eventually he said the word "London," and the news was broadcast on the stadium PA system.
"The kids ran around screaming for a while, as did the staff," Jo Doyle, director of sport at the school, recalled. "It was an extraordinary day. My ultimate aim for the Olympics is to see some kids I know taking part."
Cumberland is a specialist sports college, with half its 1,000 children entitled to free school meals and almost half coming from a mixture of ethnic minority backgrounds.
"We're really focusing on the Year 7s because they will be 18 or 19 in 2012," Mr Doyle said. "They have five years at the school to discover what their sport is, and train for it."
He said the arrival of the Olympics had also made local sports clubs much more active, whether it was in badminton, netball, football or rowing.
"With such a huge focus on sport, you can say to kids that there is nothing stopping them from being in the Olympics."
Two hopefuls at the school are Year 9 students Marco Nunes, and Lucy Goodhew.
Marco plays football for West Ham's Young Hammers, despite being an Arsenal fan, and also sprints and plays basketball. "I think it's great that the Olympics is happening in London, and I am definitely looking forward to it," he said.
Lucy is a swimmer who specialises in backstroke, is excellent at karate and a keen gymnast. "Having the Olympics here is going to push me harder to take part," she said. "It will make the whole area better, and bring in a lot of people to see what a good country this is."
Until July this year, the school had no playing fields, only a concrete playground and an old sports hall described by Jane Noble, headteacher, as dreary, cold and out-of-date. Since moving to a new site, Cumberland now has a football and rugby pitch, and outdoor tennis and netball courts. An indoor athletics centre is being built next door. "The contrast is very sharp," Ms Noble said. "The new facilities have been a great morale booster, and have helped give the children confidence.
"You can't separate academic success from health and fitness issues. This area is something of a health blackspot. There is a duty on us to make sure our children as healthy as possible - by giving them good school meals and two hours of PE every week.
"Unemployment is another big issue. The Olympics will create amazing employment opportunities, and we've got to make sure that local people end up doing the jobs."