Salvador Llinares is Professor of Mathematics Education at University of Alicante, Spain. He has participated in the Encyclopedia of Mathematics Education (Springer, 2014), the International Encyclopedia of Education (Elsevier, 2010) and serves as associate editor of the Journal of Mathematics Teacher Education.Olive Chapman is Professor of Mathematics Education at the University of Calgary, Canada. She served as editor-in-chief of the Journal of Mathematics Teacher Education and a member of the Board of Directors of the National Council of Teachers of Mathematics.