Small classes. High standards. More money. These popular remedies for school ills aren'tas effective as they're sometimes thought to be. That's the somewhat controversial conclusion of education researcher John Hattie.

Over his career, Hattie has scrutinized more than 1,000 "meta-analyses," looking at all types of interventions to improve learning. The studies he's examined cover a combined 250 million students around the world.

Out of that, he's identified five common ideas in education policy that he says should be looked at with a critical eye. NPR Ed spoke with Hattie, a professor at the University of Melbourne in Australia, about each of these five ideas following the publication of his 2015 paper "What Doesn't Work In Education: The Politics of Distraction."

1. Achievement standards."It seems very sensible. You set up minimum standards you want students to reach. You judge schools by how many reach them," Hattie says. "But it has a very nasty effect. All those schools who take kids in difficult circumstances are seen as failures, while those who take privileged students and do nothing are seen as successful."

By the same token, it seems to make sense to set achievement standards by grade level, but the further along students get in school, Hattie points out, the more of them are performing either behind or ahead of the schedule that's been set.

The alternative: a focus on growth and progress for each student, no matter where he or she starts.

2. Achievement tests. High-performing schools, and countries, don't necessarily give more standardized tests than low performers. They often give fewer.

The alternative: testing that emphasizes giving teachers immediate, actionable feedback to improve teaching.

3. School choice.Many education reformers tout school choice as a tool for parent empowerment and school improvement through competitive pressure. But Hattie says his research shows that once the economic background of students is accounted for, private schools offer no significant advantages over public schools, on average. The same goes for charter schools.

But there is one kind of choice that Hattie does believe makes a difference: teacher choice. Being able to select the best teacher for your child, Hattie suggests, could be truly empowering for parents — albeit a challenging strategy for a school to adopt.

4. Small class size. In the U.S., groups such as are dedicated to the proposition that fewer students per teacher is a recipe for success. This, Hattie argues, would come as a surprise to Japan and Korea, which have two of the highest-performing education systems in the world – and average class sizes of 33.

Hattie says reducing class size can have a positive impact. But that small class size needs to be paired with training and support for teachers to collaborate more closely with students, offer more personalized feedback and measure student improvement on a more granular level.

5. More money.Korea and Finland far outscore the U.S. on the international PISA exam, which tests learning in math, science and reading. And those two countries spend $60,000 and $75,000 respectively per student, for schooling from first grade through high school graduation. That compares with $105,000 spent per student for the same block of time in the U.S.

Hattie believes $40,000 per student for these years of education is necessary for reasonable school performance. But above that, he sees almost no relationship between money spent and results earned.

In his book Visible Learning Into Action, Hattie looks at the flip side – the ideas that dowork in schools around the world. Boiled down, he says, the most effective ideas are those that empower teachers to collaborate closely with students and support them in continuously improving.

A version of this story was published on NPR Edin August 2015.

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