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【病例1】把一块长18米,宽12米的长方形菜地平均分成3份,每块小长方形菜地的周长是多少?病症:(18+12)×2=60(米),60÷3=20(米)。诊断:此题出错的主要原因是没有联系实际情况,错误地以为只要把周长平均分成3份,即用周长除以3就行了。其实要解答这一题,可以先画出示意图,然后把要求图形的周长标出来,就很容易看出,小长方形也是由四条边围成的,再逐步解答。处方:在准确理解题意的基础上画出示意图,用彩笔将要求的周长标
[Case 1] An 18-meter-long, 12-meter-wide rectangular vegetable field is divided equally into 3 parts. What is the perimeter of each small rectangular vegetable field? Symptoms: (18 + 12) × 2 = 60 ÷ 3 = 20 (meters). Diagnosis: The main reason for this error is not linked to the actual situation, wrong to think that as long as the average permutation is divided into 3, that is, the perimeter divided by 3 on the line. In fact, to answer this question, you can draw a schematic diagram, and then mark the circumference of the required graphics. It is easy to see that the small rectangle is surrounded by four edges, and then step by step. Prescriptions: In the accurate understanding of the questions on the basis of drawing a sketch map, with colored pencils will be required weekly standard