John Hattie is Emeritus Laureate Professor at the Graduate School of Education, University of Melbourne, Australia. He is one of the world's best-known and most widely read education experts, and his Visible Learning series of books have been translated into 29 different languages and have sold over 2 million copies.

Klaus Zierer is Professor of Education at the University of Augsburg, Germany, and Associate Research Fellow of the ESRC-funded Centre on Skills, Knowledge and Organisational Performance (SKOPE) at the University of Oxford, UK. He has translated Visible Learning into German and published several works with John Hattie.