一、数概念的扩充小学数学中进行了两次数概念的扩充:即以自然数为基础,引进数零,把数概念扩充为(非负)整数,这是数概念的第一次扩充;随后引进(正)分数,把数概念扩充为(非负)有理数,这是数概念的第二次扩充。这就为中学代数有关数概念的教学打下基础。初中代数第一册,为了表示具有 Expansion of the concept of numbers and numbers The expansion of the concept of two numbers in elementary school mathematics was based on the introduction of the number zero from natural numbers and the extension of the concept of numbers to (non-negative) integers, which was the first expansion of the concept of numbers; The (positive) score, which expands the concept of numbers to (non-negative) rational numbers, is the second extension of the concept of numbers. This lays the foundation for the teaching of middle school algebra related concepts. The first volume of junior high school algebra, in order to express