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一、分数乘法●分数乘以整数的教学要点。1．分数乘以整数的意义:教学时可首先复习整数乘法的意义与同分母分数的加法,然后通过实例,先列出加法算式,再引导学生把加法算式改写成乘法算式,以此说明分数乘以整数的意义和整数乘法的意义相同,就是求几个相同加数的简便运算。2．分数乘以整数的计算方法。教学时可以采用分析对比的方法,引导学生自己归纳出计算方法。例如在例1教学中可以采取如下板书和分析方法。2/9+2/9+2/9+2/9=(2+2+2+2)/9=8/92/9×4＝2×4/9=8/9通过上述板书的比较,让学生理解,求学4个2/9的和用加法计算时,只把分子相加,分母不变;用乘法计算时,也只要把分子的4个2连加改成用4去乘分子2,分母不变,从而引导学生在理解的基础上归纳出分数乘以整数的法则即用分数的分子和整数
First, the fractional multiplication ● fraction multiplied by the integral teaching points. 1. The meanings of fractions multiplied by integers: First, we review the meaning of integral multiplication and the addition of the same denominator in teaching, and then list the addition formula first by example, and then guide the student to rewrite the addition formula as a multiplicative formula to show that the score is multiplied by The meaning of integers and integer multiplication mean the same, is to seek a few simple addition of the same number of operations. 2. The calculation of the fraction multiplied by an integer. Teaching can be used to analyze the contrast method to guide students to summarize their own calculation methods. For example, in the teaching of Example 1 can take the following form and analysis methods. 2/9 + 2/9 + 2/9 + 2/9 = (2 + 2 + 2 + 2) / 9 = 8/92/9 × 4 = 2 × 4/9 = 8/9 , So that students understand and study four 2/9 and the addition is calculated, only the numerator, the denominator unchanged; multiplication calculation, but also as long as the molecules of 4 plus 2 to 4 2, the same denominator, so as to guide students in the understanding based on the sum of fractions multiplied by the law of the rules that use fractional molecules and integers