北师大版小学数学四年级上册“参观花圃”是三位数除以两位数第二课时的教学,重点解决试商问题。试商是小学数学计算教学的难点之一,本课时的教学内容同时又是本单元学习的重点,选择这部分内容进行示范性教学很有挑战性。最近,我有幸观摩了一位省数学特级教师对本课时的教学,这位老师对教材给的情境进行了颠覆性革新,复习题、例题、练习题、孕伏题等,情境都取自“9· Beijing Normal University version of elementary school mathematics grade four volumes ”visit the flower garden “ is the teaching of the third digit divided by two digits during the second class, focusing on solving the problem of trial business. Trial business is one of the difficulties in teaching mathematics calculation in primary school. At the same time, the teaching content of this lesson is also the key point of this module. It is very challenging to choose this part for demonstration teaching. Recently, I was fortunate enough to observe a provincial math teacher to teach this lesson, the teacher on the teaching materials to the context of subversive innovation, review questions, examples, exercises, pregnancy problems, the situation is taken from ” 9·