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一、练习背景“用字母表示数”第一节课(八册1～3面)的教学内容,是在利用加减、乘除关系求未知数的基础上(五、六册)引伸、发展的.它不仅要学生用字母a、b等表示某数量关系中的一个数量,或用字母a、t等表示某一完整的数量关系,而且还要求学生会用数字去替换有关字母,算出结果,从而形成用字母表示数的完整概念.用字母表示数,虽在五、六册求未知数x中有所渗透,但那是用x去取代式中的( ),仍有具体、形象的特点,学生容易理解和接受.而这节课的教学,要求学生用他们不认识的a、b、t、s等去表示数量关系,使具体概念抽象化,加上a×t可以写成a·t或at等,也是学生从未接触过的知识,这就构成了本节课的难点,需要认真设计练习,来突破这一难点.
First, the exercise background “number of letters ” The first lesson (eight volumes 1-3) teaching content is based on the use of addition, subtraction, multiplication and division based on the unknown (5, 6 volumes) extension, development It not only requires students to use the letters a, b, etc. to represent a number of relations in a number, or use the letters a, t, etc. to represent a complete relationship between the numbers, but also requires students to use numbers to replace the letters, calculate the results, Thus forming a complete concept of the number of letters with alphanumeric representation, although in five or six seeks unknown number x in some infiltration, but that is to use x to replace (), there are still specific, the image of the characteristics, Students easily understand and accept the teaching of this lesson, require students to use their do not know a, b, t, s, etc. to represent the quantitative relationship, abstraction of the specific concept, plus a × t can be written as a · t or at, etc., but also students never touched knowledge, which constitutes the difficulty of this lesson, you need to carefully design exercises to break through this difficulty.