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比较是一种思维方法,它能帮助学生透彻地理解概念,牢固地掌握概念。我在教学“判断一个分数能否化成有限小数的方法”时,就先后三次运用了比较方法。教师出示6个分数(有意识地把它们分成两组,见下面板书),让学生把它们分别化成小数(不能整除的保留三位小数)。为下面的比较提供了“背景”材料。(板书如下) 第一次比较:学生观察计算结果发现,左边的分数能化成有限小数,而右边的分数不能化成有限小数。这是为什么呢?其中有什么规律吗?就在学生发现了问题却不能解决时,我及时指导学生比较两组分数的分子:分数的分子相同,但有的能化成有限小数,而有的不能化成有限小数。说明一个分数能否化
Comparison is a way of thinking, it can help students understand the concept thoroughly, firmly grasp the concept. When I was teaching “to judge whether a score can be turned into a finite number of decimals,” I used comparative methods three times in succession. The teacher presents 6 points (consciously dividing them into two groups, see below) and ask them to separate them into decimals (three decimal places are not divisible). The “background” material is provided for the comparisons below. The first comparison: Student observations The calculation shows that the left fraction can be converted into a finite fraction, whereas the right fraction can not be converted into a finite fraction. This is why? What is the law? In the students found the problem can not be solved, I promptly guide students to compare two groups of molecules: the same fraction of molecules, but some can be turned into finite decimal, and some can not Into a finite decimal. Explain whether a score can be reduced