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一、教材简析在四年级第一学期,学生已学习了四则混合运算顺序和带有小括号的四则混合式题.本单元是在此基础上让学生进一步巩固和熟练.应用题训练,本单元安排了用综合算式解答“相遇问题”和“一般的三步计算”的应用题.二、教学建议1.四则混合运算.这部分内容的教学要在复习旧知识的基础上进行.教学例1、例2时,先让学生说说计算步骤,提醒学生观察算式的特征,注意应用运算定律使一些计算简便.如,例1计算到第三步355+780+45时,注意启发学生用加法交换律和结合律进行简算.
First, the textbook analysis In the first semester of the fourth grade, students have learned four mixed arithmetic sequence and four mixed questions with parentheses on the basis of this unit to enable students to further consolidate and proficiency. The unit arranges the answer to the question of “encounter problem” and “general three-step calculation” by using the comprehensive formula. Second, teaching suggestions 1. Four mixed operations. The teaching of this part should be based on the review of old knowledge. 1, Example 2, let the students talk about the calculation steps to remind students to observe the characteristics of the formula, pay attention to the application of the law of some calculations so that, for example, calculated in the third step 355 +780 +45, pay attention to inspire students Addition of exchange law and law of combination of simple calculations.