Treasury secretary Gabriel Makhlouf has angered the primary teachers' union by suggesting money saved on a small rise in class sizes could be spent on improving the quality of teachers, which was far more important.
He advocated a system that recognised and rewarded "master teachers" with higher pay and dismissed the notion that all teachers were equally effective.
"Class size matters, but the quality of teaching matters more," he said in a speech in Wellington yesterday.
Mr Makhlouf also appeared to go into bat for the controversial national standards, saying: "I find it frankly incomprehensible that data on student achievement is seen as dangerous.
"Yes, data can be misinterpreted and misunderstood. But its value is immense and all organisations need data and information to help them improve."