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乘法分配律是教学中的一个重点又是难点,学生对它难于理解又难以应用。如何突破这个难点呢?笔者曾就设计专项练习、指导综合应用入手,作了初步的探索。 一、重视结构特征的训练 掌握乘法分配律的结构特征是学好它的基础,也是用好它的前提。 1.判断型练习 (1)判断下面各题,看哪道算式正确,如不正确,请指出错的原因。 ①14×38+14×62=(a)(38+62)×(14+14) (b)(38+62)×14 ②35×(43+11)=(a)35×43+35×11 (b)35×43+11 学生刚开始学习时经常会出现有错误的算法,通过辨别正误,分析说理,能加深理解,防患于未然。 (2)请你观察下面两组算式,然后回答问题
Multiplication distribution law is a key teaching point is difficult, difficult for students to understand it and difficult to apply. How to break through this difficulty? I have designed the special exercises, guidance comprehensive application start, made a preliminary exploration. First, pay attention to the training of structural features Master the structural characteristics of multiplication assignment law is to learn its foundation, but also make good use of its premise. 1. Judgment exercise (1) to determine the following questions, see which formula is correct, if not correct, please indicate the cause of the error. ① 14 × 38 + 14 × 62 = (38 + 62) × (14 + 14) (38 + 62) × 14 ② 35 × (43 + 11) = 35 × 43 + 35 × 11 (b) 35 × 43 + 11 Students often have erroneous algorithms when they first begin their studies. By making a correct distinction between correctness and error, analysis of reasoning can deepen understanding and take preventive measures. (2) Please observe the following two sets of equations, and then answer the question