Dr. John Hattie has been Professor of Education and Director of the Melbourne Education Research Institute at the University of Melbourne, Australia, since March 2011. He was previously Professor of Education at the University of Auckland. His research interests are based on applying measurement models to education problems. He is president of the International Test Commission, served as advisor to various Ministers, chaired the NZ performance based research fund, and in the last Queens Birthday awards was made “Order of Merit for New Zealand” for services to education. He is a cricket umpire and coach, enjoys being a Dad to his young men, besotted with his dogs, and moved with his wife as she attained a promotion to Melbourne. Learn more about his research at www.corwin.com/visiblelearning, and view his Corwin titles here. Dr. Arran Hamilton is Group Director of Strategy at Cognition Education. His early career included teaching and research at Warwick University and a stint in adult and community education. Arran transitioned into educational consultancy more than 15 years ago and has held senior positions at Cambridge Assessment, Nord Anglia Education, Education Development Trust (formerly CfBT) and the British Council. Much of this work was international and focused on supporting Ministries of Education and corporate funders to improve learner outcomes.