The royals visited an academy school in south-east London to attend the launch of a new project that is being supported by their charitable Foundation.
In recognition of London hosting the Olympics, the Foundation has created a sports programme – Coach Core – with the organisation Greenhouse, one of the charities that benefited from the Cambridges’ wedding fund.
The Duke and Duchess of Cambridge, Team GB and ParalympicsGB Ambassadors, arrived in a chauffeur-driven limousine all casually dressed for the occasion.
Youngsters playing judo, basketball, five-a-side football and table tennis were put through their paces by the coaches as Their Royal Highnesses watched.
The Coach Core programme is being piloted by Greenhouse and will train 16 to 19-year-olds to become qualified coaches and mentors for their schools and communities.
The hope is that the talented young sportsmen and women will be able to inspire their students and build a future for themselves in sport.
If it proves successful, the Foundation aims to roll out the initiative to other sectors where inspirational young coaches can become role models for and inspire young people.
The Duke walked on to the five-a-side football pitch where dozens of schoolchildren were practising shooting, dribbling and passing skills.
The Duke was joined by Michael de Giorgio, Chief Executive of Greenhouse, and chatted to some of the coaches who were taking the lessons.
But The Duke could not resist joining in and lined up with a group of youngsters for shooting practice.
The royal shimmied through some cones then passed the ball to a trainer who returned it for the shot, but The Duke hit it just wide of an empty goal.
With his head bowed he trudged back to the middle of the pitch but a few minutes later had the chance to redeem himself when the students were asked to volley the ball into the net.
As His Royal Highness ran forward the trainer threw the ball into the air and shouted “keep your eyes on it”. The royal sent it just over the bar but received the encouraging comment “much better” from the coach.
The Duke blamed his lack of prowess in front of goal on the loafers he was wearing, telling one of the youngsters it was “obviously” the shoes.
He later gave a speech in which he highlighted the importance of sport: "Over the next month, the eyes of the world will be on Great Britain. For us to hold the Olympic and the Paralympic Games here in London is a great moment for our nation, which itself is steeped in sporting history.
“Therefore, for Catherine, Harry and me there could be no better way of starting this epic time than being with you here in Rotherhithe, so close to the heart of London 2012, to launch Coach Core.
“Watching me on the football field is never a pretty sight – the expression giraffe on ice springs to mind. However, it is marginally less embarrassing than seeing my brother cheat his way to becoming the fastest man on the planet.
“Catherine, on the other hand, with a tennis racket or a hockey stick is something to behold and be aware of.
“But what all three of us have in common is that we love sport. And not just playing it, but for what it does for people young and old. It builds confidence, engenders mutual respect and responsibility, and teaches us about the value of team work.
“That’s why Catherine, Harry and I are so excited about Coach Core, this brilliant programme developed by the Greenhouse Charity in partnership with our foundation.”