在学会了计算20以内的加减法后,我们常常要利用这些知识解答一些变式练习。例:在括号内填上适当的数。4+9=()+8错误解答:4+9=(13)+8错解分析:上面的解答显然是错误的。为什么会犯这样的错误呢?说到底,就是小朋友没有看完整个题目,见到括号就填,当然就会解错。等号两边有两个算式,说明两个算式的得数相等。等号 After learning to calculate the addition and subtraction within 20, we often use this knowledge to answer some variant exercises. Example: Enter the appropriate number in brackets. 4 + 9 = () + 8 Wrong Answer: 4 + 9 = (13) +8 Decomposition Analysis: The above solution is obviously wrong. After all, why do children make such mistakes? After all, they did not read the whole topic, but after they saw the parentheses, they would certainly be wrong. There are two formulas on both sides of the equal sign, indicating that the equal numbers of the two formulas are equal. equal sign