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在小学数学教学中,我们应重视学生的动手操作,让学生在摆弄教具中学习知识。现以三例说明。一、让学生用8个红三角形与5个黄三角形学具演示8+5,可能会出现以下几种合并过程:(1)将两种三角形先合并在一起,然后一个个地去数,从1数到13;(2)将红三角形逐个放入黄三角形的行列中,边放边数,从6数到13;(3)将黄三角形逐个放到红三角形行列中,从9数到13;(4)从红三角形里拿出5个与黄三角形凑成10,再把余下的3个红三角形合并过来,从而得到13;(5)从黄三角形里拿出2个与红三角形凑成10,再把余下的3个黄三角形合并过来,从而得到13。学生交流自己的操作过程后,在教师的引导下进行几种方法的比较,就会领悟到第一种方法最慢且容易数错,第五种方法最快且不易错。这时,让全班学生再用第五种方法重新操作一遍,就能容易地概括出凑十法的思路,而且能自觉地接受用大数凑十来进位加的方法,既培养了计算能力,又初步训练了思维能力。二、教学“小数点位置移动引起小数大小变化”的内容时,我在讲清小数点移动的变化规律以后,指导孩子们动手做了一个数学
In primary school mathematics teaching, we should attach great importance to the students’ hands-on operation, let students learn to play with the teaching aids. Now with three examples. First, let the students demonstrate 8 + 5 with 8 red triangles and 5 yellow triangles. The following several merging processes may occur: (1) The two triangles are combined first and then one by one, from 1 to 13; (2) The red triangle one by one into the ranks of the yellow triangle, aside the number of sides, from 6 to 13; (3) the yellow triangle one by one into the red triangle ranks from 9 to 13 ; (4) 5 out of the red triangle and the Yellow Triangle made 10, then the remaining three red triangles merged to get 13; (5) from the yellow triangle out of two and red triangle made 10, and then merge the remaining three yellow triangles to get 13. Students exchange their own operation process, under the guidance of the teacher several ways to compare, you will realize that the first method is the slowest and easy to count the wrong number, the fifth method is the fastest and not easy to wrong. At this time, letting the whole class re-use the fifth method again, it is easy to summarize the idea of putting together ten methods and can consciously accept the method of using a large number of decimal places to carry one’s place and train both the computing power , But also preliminary training of thinking ability. Second, the teaching of “the decimal point position changes caused by the size of the decimal ” content, I clarify the rules of change of the decimal point to guide the children to do a math