或许是为了考虑儿童的认知特点,也或许是为了考虑数学的简化便捷,在小学数学的教材里出现大量的、具有“约定俗成”的符号、概念、定义、法则等内容。这些“约定俗成”的符号、概念、定义、法则对于教师来说是“一目了然”的,以至于这些“约定俗成”的内容已成为我们教师漠视的领域。然而正是我们教师的漠视,导致许多“约定俗成”的符号、概念、定义、法则难以进入学生的认知体系,成为学生学习数学的难点。为此,我们有必要重新审视这些“数学规 Perhaps to consider children’s cognitive characteristics, perhaps to consider the convenience of mathematics, mathematics in primary school textbooks appear a large number, with ”conventional “ symbols, concepts, definitions, rules and so on. These ”conventions“ symbols, concepts, definitions, and laws are ”at a glance“ for teachers so much that these ”conventional“ content has become an area that our teachers ignore. However, it is our teacher’s indifference, which leads to many symbols, concepts, definitions and laws difficult to enter the cognitive system of students and becomes a difficult point for students to learn mathematics. For this reason, we need to re-examine these ”mathematical rules