运算定律的推导有助于培养学生的抽象概括能力和计算能力。小学数学第八册涉及加法交换律、结合律，乘法交换律、结合律、分配律的推导与应用。教学中应在推导和应用上下功夫。一、遵循教材编排的规律．抓好公式推导过程中的四个层次1．由一个可以用两种方法解答的应用题引入， The derivation of the law of arithmetic helps to develop students' abstract abilities and computing abilities. The eighth volume of elementary mathematics deals with the derivation and application of the law of addition, the law of combination, the law of exchange in multiplication, the law of combination, and the law of distribution. Teaching should be in the derivation and application work hard. First, follow the rules of textbook layout. Do a good job in the process of formula derivation of the four levels 1. Introduced by an application that can be answered in two ways,