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一、明理找依据,培养思维的深刻性在小学数学五年级上册第三单元《练习四》中有这样一道“?”号题:“如图所示的这间厨房地面要铺正方形地砖,需选用边长为多少方分米的砖,才能铺得既整齐又节约?(地砖的边长要求整数分米。)”学生一共列出了这样一些算式:(1)(30×24)÷(1×1)(2)(30×24)÷(2×2)(3)(30×24)÷(3×3)(4)(30×24)÷(6×6)然后我要求学生一一说出每种方法的理由,逐步弄清楚各种方法的依据分别是什么。通过说理,使学生明白方砖的边长必须既是30的因数,又是24的因数。
First, the reason to find a basis to cultivate the profound nature of thinking In elementary school mathematics fifth grade on the third unit “practice four” there is such a “? ” Question: “As shown in the kitchen to shop square Floor tiles, the need to use the side length of the number of square meters of brick, in order to shop both tidy and save? (The length of the floor tiles require an integer decimeter.) ”Students altogether lists such a formula: (1 24 ÷ 1 × 1 2 × 30 × 24 ÷ 2 × 2 3 × 30 × 24 ÷ 3 × 3 4 × 30 × 24 ÷ 6 × 6 Then I asked the students to explain the rationale for each method one by one and gradually figure out what the respective methods are based on. Through reasoning, to make students understand that the side length of the brick must be both a factor of 30 and a factor of 24.