一、教学实录片段一:(复习加法交换律后)师:同学们学得那么好,老师讲一个故事给你们听,怎么样?有一天,数学老师在班里出了一道题,要他们算出1+2+3+…+100的得数。同学们都愁了,这个题目肯定要算到下课才能算出来。可是,过了5分钟,一个小朋友举起了手说出了答案,而且答案非常准确。这个小朋友长大以后成了有名的数学家,他的名字就叫做高斯。 First, the teaching of Record A: (review after addition exchange law) Teacher: Students learn so well, the teacher tells a story to you, how? One day, math teacher in the class out of a question, asking them to calculate 1 + 2 + 3 + ... + 100. Students are unhappy, this subject must be counted to get out of class can be calculated. However, after 5 minutes, a child raised his hand and said the answer, and the answer is very accurate. The child grew up later became a famous mathematician, his name is called Gaussian.