Bianshi teaching explains the paradox of Chinese learners very well. As an important form of bianshi teaching, ``one problem multiple change'' widely exists in classrooms of Chinese mathematics teachers. Based on three different examples of this method, the present paper shows how Chinese mathematics teachers do it in classroom, and further discusses the position, function and value of this method in mathematics classroom teaching in China. At the same time, this can further explain the phenomenon of ``Chinese learner paradox''.