"Actually the truth is that is dramatically changing. We are succeeding. And we should be very proud of what New Zealand is capable of."
But voters wanted to talk about other issues. They wanted to know when house prices would come down, how National planned to address child poverty, and when Resource Management Act reforms would get back on track.
Later, Mr Key faced questions about his choice of words when he told RadioLive that Kim Dotcom was Internet Party leader Laila Harre's "sugar daddy".
"He funds her. It's totally accurate," he told reporters, after Ms Harre took offence and said his comment was sexist and defamatory.
"[A sugar daddy is] someone who funds somebody else. You have to go and ask what she's exchanging it for. I think she's exchanging it for giving him a way around the justice system."
Students in Porirua and Raumati quickly diverted Mr Key from his script, grilling him on everything from the Israel conflict to his favourite band during a series of Q&A sessions.
Students at Discovery School in Porirua asked whether he had a stunt double. Sort of, he said: "Bill English."
What would he do if he was not a politician? He'd be a pilot or a butcher, Mr Key replied.
The kids' questioning uncovered one notable u-turn - the Prime Minister's favourite music has now changed from "easy listening" to boyband One Direction.
Students at Kapiti College applied a little more pressure.
Would he intervene in Gaza? What is he doing about the gap between rich and poor? And would he raise the minimum wage?
Asked whether he would legalise medical marijuana, he told the school assembly: "This is the fundamental message. Drugs are bad for you."
The students' grilling could not last forever. They soon reverted to patsy questions.
"Can I have a hug?" a Kapiti College student asked, before rushing across a crowded assembly hall for a bear-like embrace with Mr Key.