Hattie's Visible Learning

A 25-year program of meta-meta-analyses ranking 250+ influences on student achievement by effect size (Cohen's d), using d = 0.40 as the hinge point above which an influence is claimed to produce above-average impact — accompanied by significant methodological critiques that careful users must read alongside the rankings.

Inside this handbook: the framework distilled, the AI-integration question that matters now, and the one move you can run Monday.