Learn more about effect size and 'Know Thy Impact' when reading this chapter review of John Hattie's book, Visible Learning for Teachers.
Visible Learning focuses largely on effect size, which Hattie refers to as the hinge point. According to Hattie, one years academic growth equals .40 and everything above that yields more than one years growth in one years time. Hattie states that 95% of the things teachers do yield growth, he was talking about everything from 0.01 effect size or greater. Visible Learning was based on more than 800 meta-analysis of 50,000 research articles while focusing primarily on the educational effect size.