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在“比的意义和性质”中,分数比的化简是教学的一个重点。课本中是用进行比的这两个分数的分母的最小公倍数去乘比的前项和后项,化成整数比,然后再化简的。例如,1/6:2/9=(1/6×18):(2/9×18)=3:4=3/4我认为,这种化简方法是比较繁琐的。在教学时,我先采用课本中的方法,让学生掌握比的基本性质的运用。然后,利用已经学过的比与除法的关系,把分数比的化简看成是分数除法计算。例如,1/6:2/9=1/6÷2/9=1/6×9/2=3/4这种方法,学生一点就明,比较容易接受。但是应该注意:(1)必须在学生理解比与除法的关系的基础上才能进行化简;(2)最后结果不把它看成是商,而看成是一个比。掌握了以上两点,再出现带分数比的化简,学生做起来就容易得多了。例如,
In the “meaning and nature of the ratio,” the reduction of the fractional ratio is a teaching priority. Textbook is the ratio of the two scores of the denominator of the least common multiple ratio to the preceding paragraph and the latter, into an integer ratio, and then simplified. For example, 1/6: 2/9 = (1/6 × 18) :( 2/9 × 18) = 3: 4 = 3/4 I think this simplification is a bit tedious. When teaching, I first use the textbook approach to enable students to master the basic nature of the use of than. Then, using the relationship between ratios and divisions that have been learned, the simplification of the fractional ratio is treated as a fractional division. For example, 1/6: 2/9 = 1/6 ÷ 2/9 = 1/6 × 9/2 = 3/4 In this way, the student is more informed and acceptably. However, it should be noted that: (1) Simplification must be carried out on the basis of the students' understanding of the relationship between the ratio and the division; (2) The final result does not regard it as a quotient but as a ratio. Mastered the above two points, and then with the score than the reduction, students do much easier. E.g,