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与整数应用题相比,分数应用题显得更加复杂而抽象,教学实践证明画线段图是抽象问题具体化的有效途径之一。一、数形结合,量率分开。例1:修一段公路,第一天修了全长的1/5,第二天修了4/5千米,还剩下全长的1/10没有修,这段公路全长多少千米?思路分析:本题中的具体数量和分率都是分数,且对应关系不明显,在画线段图时,如果把分率和具体数量都表示在线段的一侧,由于量率没有分开,所以不但不能显现出量率对应关系,还容易让学生产生误解,分析数量关系产生干扰。
Compared with integer problem, fractional problem is more complicated and abstract, and teaching practice proves that line drawing is one of the effective ways to concrete abstract problem. First, the combination of figures, the rate of separation. Example 1: Repair a section of the road, the first day of the repair of the full length of 1/5, the next day repair 4/5 km, leaving the full length of 1/10 no repair, how many kilometers of this road length? Analysis: The specific number and fraction of this question are scores, and the corresponding relationship is not obvious, when drawing the line segment, if the fraction and the specific number are expressed on one side of the line segment, because the rate is not divided, so not only can not Showing the corresponding relationship between the volume rate, but also easy to make students misunderstand, analyze the relationship between the number of interference.