**Gila Hanna** is Professor Emeritus at the University of Toronto. She taught graduate courses in mathematics education and in measurement and evaluation; she also led a large number of research projects and supervised several Ph.D. and M.A. theses in mathematics education. Her primary research interests are the role of proof and truth in mathematics and mathematics education, and gender issues in mathematics teaching and learning. She has been Convenor of the International Organisation of Women and Mathematics Education (1988-1992), Vice-Chair of the Canadian Mathematics Education Study Group (1986-1990), and has served on several Social Sciences and Humanities Research Council of Canada (SSHRC) adjudication committees and on the scientific program committees of a number of international conferences on mathematics education. From 1989 to 2000 she was Co-Editor of the international journal *Educational Studies in Mathematics* and is now one of its Advisory Editors. From 2000 to 2007 she was Co-Founder and Co-Editor of the *Canadian Journal of Science, Mathematics and Technology Education.* She served as Co-Chair of ICMI Study 19 on proof and proving in mathematics education. She has published extensively on proof and other aspects of mathematics education, and has delivered lectures at several universities as well as at numerous international conferences on mathematics education. In 2003 she was appointed “Fields Institute Fellow”, a lifetime appointment conferred on certain individuals who have made outstanding contributions to the Fields Institute for Research in Mathematical Sciences, its programs, and to the Canadian mathematical community.

After teaching mathematics and science at high school for a few years, **Michael de Villiers**, received the Science Teacher of the Year award in South Africa in 1983. Later that same year he was appointed as a researcher at the Research Unit for Mathematics Education of the University of Stellenbosch, South Africa. He has been at the University of Durban-Westville since 1991 (Univ. of KwaZulu-Natal since 2004) where he teaches both under-graduate and graduate courses in mathematics & mathematics education. He has published 7 books and over 170 articles peer reviewed articles in mathematics and mathematics education, many of which have been in international journals. Two special points in a triangle have been named after him.

Between 1988-1997, he was editor of Pythagoras, the official research journal of the Association for Mathematics Education of South Africa (AMESA). He is a regular speaker at local and international conferences on mathematics and mathematics education. His main research interests are Geometry, Proof, Applications and Modelling, and the History and Philosophy of Mathematics. Since 1997, he has also been vice-chair of the SA Mathematics Olympiad Committee which is responsible for setting and organizing the nationwide South African Mathematics Olympiad, seeing a growth of participation from less than 10000 to over 60000 currently.