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一、直观、操作、建立“倍”的概念学好求一个数的几倍是多少的应用题的关键是建立“倍”的概念。为了使学生切实理解并掌握“倍”的概念,可以采取以下方法:1.直观,初步知道“倍”的概念。教学时,教师可充分利用教材第74页的准备题。教师先在计数器上杆拨2颗算珠(一次拨上,不要一次拨一颗),在下杆上也拨2颗(一次拨2,并与上杆的两颗对齐),再在下杆上连续拨三次算珠(两颗两颗地拨,且每2颗之间都留一定的间隔,使学生一眼就能看出下杆的算珠有4个2颗)。拨完后,提问:下杆拨了几个2颗?(生:4个2颗)然后教师讲解:“上杆有2颗算珠,下杆有4个2颗,我们就说下杆上算珠的颗数是上杆算珠的4倍”。接着,教师一边连续地从下杆上每次拨去两颗算珠,一边提问学生:现在下杆上的算珠有
First, the intuitive, operation, the establishment of the concept of “times” Learning to find a few times the number of applications is the key to the establishment of “double” concept. In order to enable students to effectively understand and grasp the concept of “times ”, you can take the following methods: 1. Intuitive, preliminary understanding “times ” concept. When teaching, teachers can take advantage of the preparation questions on page 74. The teacher first dials 2 counting beads on the counter (one dial, do not dial one at a time), also dials 2 on the lower bar (dial 2 at a time and aligns with the two on the upper bar), and then continues on the lower bar Dial three count beads (two two to dial, and between each two have a certain interval, so that students can see a bar under the counting of four 4). After dialing, ask: how many next 2? (Students: 4 2) Then the teacher explained: “on the pole with 2 beads, the next bar has 4 2, we say under the bar Count the number of beads on the bead 4 times ”. Then, while continuing to dial two beads each time from the lower pole, the teacher asks the student: Now the bead on the lower pole has