Celia Hoyles is Professor of Mathematics Education, London Knowledge Lab, Institute of Education University of London, UK.Richard Noss is Professor of Mathematics Education and Co-director of the London Knowledge Lab, Institute of Education University of London, UK.Philip Kent is a Research Officer, London Knowledge Lab, Institute of Education University of London, UK.Arthur Bakker is a Research Officer in the TmL project, currently at the Freudenthal Institute, Utrecht University, the Netherlands.