“商不变性质”是除法简便运算的依据,又是学习小数除法和分数基本性质的基础。教学时我紧扣教学内容,围绕教学重点精心设计了以下五个层次练习。一、准备练习,作好铺垫1.口答: 学生口答后,教师指出:6乘以2、4、8可以说成把6扩大2倍、4倍、8倍;48除以2、4、8可以说成把48缩小2倍、4倍、8倍。2.顺着箭头方向,说出扩大或缩小多少倍。[“商不变性质”比较抽泉,概念较多,而“扩大”、“缩小”是性质中的两个重要概念,学生第一次接 The “invariable nature of business” is the basis for the division of simple operations and the basis for learning the basic properties of fractional division and scores. Teaching closely linked to teaching content, focus on teaching carefully designed the following five levels of practice. First, prepare to practice, paving the way 1. Mouth answer: After the students mouth answer, the teacher pointed out: 6 multiplied by 2, 4, 8 can be said to be 6 to expand 2 times, 4 times, 8 times; 48 divided by 2,4,8 It can be said to reduce 48 times 2 times, 4 times, 8 times. 2 along the arrow direction, say how many times to expand or shrink. [“Invariant nature” is more spring, the concept of more, and “expand” and “reduce” is the nature of the two important concepts, the first time the students