100以内加减法是第二册数学的重点内容之一,是整数“二十以内”、“百以内”、“万以内”、“多位数”四个阶段中承前启后的关键阶段。由于20以内加减的数值范围小,又基本接近六、七岁儿童的生活实际,教学难度不大。而百以内的加减不但数值扩大了,同时数位概念、计算法则等都相应拓宽,所以在学习过程中尽管能初步学会算理和掌握算法,而计算的结果却常常出现差错。因此 The addition and subtraction within 100 is one of the key contents of the second volume of mathematics. It is the crucial stage in the four stages of integer: less than twenty, less than one hundred, less than one million, and more than one digit. As the numerical range of addition and subtraction within 20 small, but also close to the actual life of six or seven-year-old children, teaching difficult. The addition and subtraction of less than one hundred not only expand the numerical value, meanwhile, the concept of digit and the law of calculation are correspondingly broadened. Therefore, although the algorithm can be learned and mastered in the process of learning, the calculation results often fail. therefore