The superior performance of East Asian students in recent international studies of mathematics achievement has attracted the attention of educators and policy makers worldwide. Xinrong Yang focuses on exploring how an expert mathematics teacher is conceptualized by mathematics educators in China and the characteristics that expert mathematics teachers share. The author adopts a sociocultural theory and a prototypical view of conception in this study of teacher expertise and shows that some of the roles expected to be played by expert mathematics teachers in China, such as being at the same...