Elizabeth de Freitas is a Professor in the Education and Social Research Institute at Manchester Metropolitan University. Her research focuses on philosophical investigations of mathematics, science and technology, pursuing the implications and applications of this work within cultural studies. She is co-author of the book Mathematics and the Body: Material Entanglements in the Classroom (with Nathalie Sinclair, Cambridge, 2014), associate editor of the journal Educational Studies in Mathematics, and has written more than fifty chapters and articles on diverse topics. Nathalie Sinclair is the Canada Research Chair in Tangible Mathematics Learning at Simon Fraser University, British Columbia. She is the author of several books, including Mathematics and the Body: Material Entanglements in the Classroom (with Elizabeth de Freitas, Cambridge, 2014) and Mathematics and the Aesthetic: Modern Approaches to an Ancient Affinity (with William Higginson and David Pimm, 2006), and over fifty articles. She has also designed educational technologies, including the touchscreen App TouchCounts and dynamic geometry microworlds for young learners at www.sfu.ca/geometry4yl. She is the founding editor of the journal Digital Experiences in Mathematics Education. Alf Coles' recently published Engaging in School Mathematics: Symbols and Experiences (2015) draws on more than twenty years of work as a teacher-researcher at both primary and secondary levels. He is on the executive committee of the British Society for Research into Learning Mathematics and is an active member of the Mathematics Education Special interest Group of the British Educational Research Association. His current interests include drawing his work in mathematics education into closer dialogue with issues of sustainability.