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Des'Ree leads the Big Sing in London
Thousands of children across the country have been trying to set a world record.
They're hoping to team up for the world's biggest simultaneous sing-along.
Ricky took his best singing voice along to help.
"Something very different went on at the 02 Arena in London this afternoon. No, it wasn't Leona Lewis or Take That performing, it was 8,000 school children singing their hearts out instead!
They were hoping to break a world record, as well as raising loads of money for charity.
Luckily, I got to take part in all the action.
It's part of an event called the Big Sing 2008, which is trying to set a record for the most people singing the same song at the same time.
They were all singing along to a song by an artist called Des'Ree - it's called You Gotta Be. It's quite an old song so you may not remember it. Organisers chose it because they thought the lyrics were inspirational.
At exactly 2.45pm thousands of kids in the Arena were linked via radio, to hundreds of schools across the UK. As soon as everyone started to sing I couldn't hear myself speak - it was really hard to do my report for Newsround!
But could they set a new world record?
When the song came to an end Des'Ree, who had turned up especially for the event, announced that they had broken the world record, with nearly 700,000 kids singing together. Believe me, it was pretty loud!
It felt great to be part of it all and to actually help break a world recordů hopefully that ringing sound in my ears will go away!"