Australia should move to bigger class sizes if it wants to improve its education system without spending more money, according to the OECD's top education guru Andreas Schleicher, and he has the data to prove it.
The highest performing countries in the OECD's PISA tests have classes significantly larger than Australia's average, he said.
But it's not the class size that's the key, he explains – it's giving teachers less class time so they can focus on high-quality teaching.
The trade-off in a finite education budget for having teachers doing just 12-16 hours of class time a week is that you have to fit more kids into their classes.
The impact of class size on education quality is a highly contested issue within the research, while smaller class sizes tend to be popular with teachers, education unions and parents.
Mr Schleicher's point is that the key factor is not the size of the class – it's the quality of teaching strategies. Given the choice between a great teacher and a small class, pick the great teacher.
"Australian teachers have relatively little time for other things than teaching compared with their Asian counterparts," he told Fairfax Media at an education conference in Dubai.
"If you're a teacher in Hong Kong, China, Japan, you teach a lot less than Australian teachers, but you actually work more.
"You have a lot more time to engage with students individually, to work with parents, to work on reviewing lessons, analysing lessons, observing practice and so on. So there's more emphasis on the professional development, particularly for higher order thinking skills.
"Those are very important. And the trade-off is bigger classes. The more popular trade-off is a smaller class, that's what everybody likes. But if you ask me what is actually going to give better outcomes, Australia should think harder about this."
As policymakers have struggled to deal with Australia's slipping performance in international benchmark tests like PISA and TIMSS, the perceived quality of teachers has come under fire.
Australia has not been as good at extending its top students, and has become less effective at mitigating socio economic disadvantage in its schools. But the OECD's research suggests the problem is how our teachers are using their time.
"Australia has many ingredients of success," Mr Schleicher said, speaking on the sidelines of the Global Education and Skills Forum in Dubai on Saturday, but our policy settings have been focusing on things that are not addressing the source of our achievement gap between students.
The reporter travelled to the Global Education and Skills Forum as a guest of the conference.