Hekia Parata needs more time to prove she's a good education minister, Prime Minister John Key says.
Mr Key on Tuesday sacked two ministers - Kate Wilkinson and Phil Heatley - but spared Ms Parata in his cabinet reshuffle although she has overseen a series of blunders and policy reversals since she was appointed.
"She's been in the portfolio for a year and the others held theirs for about four years," Mr Key said on Radio New Zealand on Wednesday.
"We need more time to gain a full assessment."
Mr Key acknowledges there have been "one or two mistakes" in education but says it's always been a controversial portfolio.
"She's done a lot of things right that she hasn't been given credit for," he said.
"I'm confident Hekia can do a good job for youngsters and parents - she's passionate about under-achievement in schools."