初中代数“幂”一节教完后,我布置了一道课外作业,要求学生背诵10到20的整数的平方。下课后,学生纷纷议论,普遍反映背不出来。乍听之下,觉到很奇怪,记忆十一个数的平方,只要花十多分钟的时间,困难在哪里呢?过而思之,觉得这主要是学生速算能力不强的缘故,此外,跟他们对数字计算缺乏兴趣,不习惯于多想善算,也不无关系。后来教“整式”一章的时候,我把如何记忆两位数平方的方法教给了他们。我认为记忆两位数的平方,其本身就是学习速算的方法,而记牢之后,又有助于迅速计算两位数的乘法,学生学会了是有好处的。为叙述方便起见,今分几点来讲。 After finishing junior high school algebra “power”, I arranged an extracurricular homework, asking students to recite the square of an integer from 10 to 20. After class, students have talked about, generally do not come back. At first glance, I feel very strange, remember the square of eleven numbers, as long as it takes more than 10 minutes, where is the difficulty? Think about it, think this is mainly due to the poor ability of calculating the speed of students, in addition, With their lack of interest in digital computing, not accustomed to think about how to be good, it does not matter. When I later taught the “Entire” chapter, I taught them how to memorize double-digit squares. I think that remembering the square of a double digit, itself, is a way of learning how to calculate a quick calculation. After memorizing it, it helps to quickly calculate a double-digit multiplication. It is good for the student to learn it. For the convenience of narration, in terms of points today.