Although only two recall tasks were used in U.S. classrooms and three in the Chinese classrooms, Chinese and U.S.
teachers dealt with these recall tasks very differently. Chinese teachers pushed students to use symbols to represent
formulas. For example, in Mr. Liu’s second lesson, he asked students to recall how to find the perimeter of a rectangle
and a square before he introduced how to find the perimeter of a circle. It took them 6 min to recall and discuss the
concept of perimeter of a rectangle and a square. Below is the excerpt of the discussion that took place during this lesson.