Binyan Xu is Full Professor in the College of Teacher Education of East China Normal University. She earned a B. Sc. degree in mathematics from East China Normal University in 1986, and a Ph.D. degree in mathematics education from University of Osnabrueck of Germany in 1994. Yan Zhu is an associate professor in the College of Teacher Education of East China Normal University. She earned a B. Sc. and M. Ed. degree in mathematics education from East China Normal University, and a Ph.D. degree in mathematics education from Nanyang Technological University of Singapore.Xiaoli Lu is a postdoctoral fellow in the Department of Mathematics of East China Normal University. She earned a B. Sc. degree in mathematics from Qingdao University, a Master’s degree in mathematics education from East China Normal University, and a Ph.D. degree in mathematics education from the University of Hong Kong