John Craven isn't the only famous presenter who's worked on Newsround! Find out who else has been on your screens in our Newsround Hall of Fame...
Helen Skelton may be a record-breaking Blue Peter presenter now, but did you know she worked on Newsround before she joined the BP team in 2008?
Sonali Shah presented Newsround from 2006 to 2011. She went all over the world to report for Newsround - here she's in a Haiti orphanage after the earthquake there in 2010. She now works for BBC Sport.
John Humphrys presents quiz show Mastermind and Radio 4's morning news programme Today. He's known for his tough interviewing skills. John worked as a reporter on Newsround earlier on in his career.
Matthew Price was a Newsround reporter from 1999-2002. Since leaving the show, he's covered loads of big news stories around the world for the BBC. In August 2011, he was working in Tripoli in Libya when he got trapped with other journalists in a hotel by gunmen supporting former leader Colonel Gaddafi.
Krishnan Guru-Murthy is now one of the main presenters on Channel 4 News, but on the left is how he looked when he presented Newsround back in 1991. We see he's ditched the fishy jumpers...
Julie Etchingham is watched by millions of viewers as presenter of the News at Ten on ITV. But she was a presenter at Newsround back in the 1990s.
BBC's Entertainment Correspondent Lizo Mzimba worked on Newsround for ten years from 1998 to 2008 as a presenter. He's now busy reporting on all the big showbiz stories for the BBC.
If you love Formula 1, then you'll know this guy - Jake Humphrey. He presented several CBBC shows, including Newsround and Sportsround, before heading off to do TV for grown-ups.
You've probably seen this guy, Nick Robinson, outside 10 Downing Street on telly. He's the top politics reporter for BBC News. Nick started his career as a BBC trainee in 1986 and worked at Newsround for three months.
John Craven was the first ever Newsround presenter. He fronted more than 3,000 bulletins and became a household name. He now presents the BBC's Countryfile. But he's not the only famous face who started out on Newsround...
Ellie Crisell worked as a reporter and presenter on Newsround from from 2003 to 2008. You might see her now on BBC News and reading the 60 second news update at 8pm on BBC One.
And Nel is the newest reporter to join the Newsround team, joining us in 2011. We've got loads of other stuff to celebrate Newsround's 40th birthday - click "Home" above to explore all our other stuff.
And these are some of the faces you'll see when you watch Newsround now. From left to right, here's Leah, Ore, Ricky, Joe and Hayley.
Kate Sanderson presented Newsround for four years from 1997 to 2001. After leaving Newsround she went on to work at BBC Breakfast and Watchdog. She's now a presenter on British Forces News.