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13 April 2015 Last updated at 07:37 BST
Mr Cameron answered their questions on topics such as immigration, what it's like to be PM, and how much it now costs to go to university.
He was also quizzed on the bad behaviour of MPs in Prime Minister's Questions - which many Newsround viewers have commented on in the past.
But one girl asked a question that left Mr Cameron stumped: if you could pick one politician apart from yourself, to win - who would it be, and why?
Newsround took some Year 7 schoolchildren to meet Conservative leader David Cameron ahead of the General Election.