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John Hattie

What Is a Large Effect Size?

Robert E. Slavin | Posted 03.10.2016 | Education
Robert E. Slavin

Ever since Gene Glass popularized the effect size in the 1970s, readers of research have wanted to know how large an effect size has to be in order to...

What Do Schools Need? Collaboration and Principals Who Lead It

Karin Chenoweth | Posted 07.01.2016 | Education
Karin Chenoweth

John Hattie has once again provided the education field an important way of thinking about building a profession grounded in evidence. And I was happy to see that he identified the power of school leaders as a key lever of school improvement.

To Test or Not to Test?

Karin Chenoweth | Posted 06.19.2015 | Education
Karin Chenoweth

I recently received an e-mail from a reader who raised a question that haunts a lot of teachers and parents: Does testing harm kids?