by Grant Wiggins
"I have been a fan of John Hattie’s work ever since I encountered Visible Learning. Hattie has done the most exhaustive meta-analysis in education. Thanks to him, we can gauge not only the relative effectiveness of almost every educational intervention under the sun but we can compare these interventions on an absolute scale of effect size.
"Perhaps most importantly, Hattie was able to identify a ‘hinge point’ (as he calls it) from exhaustively comparing everything: the effect size of .40. Anything above such an effect size has more of an impact than just a typical year of academic experience and student growth. And an effect size of 1.0 or better is equivalent to advancing the student’s achievement level by approximately a full grade."