Reflection on the composition of the second grade in the teaching of oral arithmetic multiplication

Yesterday, we learned oral arithmetic, which was based on the calculation of double digits multiplied by one digit last semester.

When teaching 15×3, I asked the children to talk about how you do verbal arithmetic. Health 1: Divide 15 into 10 and 5,10× 3 = 30,5× 3 =15,30+15 = 45. Health 2: I want to do the calculation by hand. 3 times 5 equals 15. Write 5 on the decimal place, 1 times 3, and then add 1 to 4, so 15× 3 equals 45. Then I asked the students who can do oral arithmetic to talk about oral arithmetic methods, and then asked the average students and students with learning difficulties to talk about oral arithmetic methods, and finally summed up oral arithmetic methods.

Through questioning and practice in class, I think the effect is ok. Thinking of such a simple verbal calculation, the child should be fine. So in the afternoon, when studying by ourselves, we did an assignment. After correcting, it is found that one third of the students in the class have mastered it well, one third have miscalculated 1 and 2, and the other third have made more mistakes.

This caused me to reflect: Why can't students master such a simple oral calculation well? Looking back on my own classroom teaching, I think the problem lies in: I just let the students say the verbal calculation method, and the students with quick thinking can hear it, which is a piece of cake for them. But for other students with slow reaction and poor spatial imagination, it is difficult. If in teaching, I can use block diagram or physical diagram, supported by intuitive representation, combined with numbers and shapes to guide students to experience the process of building mathematical models and help students understand arithmetic and master algorithms, the effect may be much better.

In view of the phenomenon that students' oral arithmetic ability is weak and their methods are not skilled, I took another oral arithmetic practice class. First, simple oral arithmetic training. Let the students say the algorithm first, then show the corresponding pictures to help the students with difficulties understand the algorithm, and then master the algorithm in step-by-step practice. Finally, consolidate the oral calculation method in specific situations and cultivate the ability to solve problems.

Questions 5 and 9 are in the form of "driving a train". Let's compare which train goes faster. Make students concentrate, take "striving to be the fastest train" as the driving force, cultivate collective consciousness and improve oral expression ability. Question 6: Take the students' favorite candied haws as the carrier, continue to train two-digit multiplication by integer ten, and learn to solve problems with the quantitative relationship of "unit price × quantity = total price".

Question 10 requires students to solve two problems (1) and (2) by using the relationship of "speed × time = distance". Item (3) is for students who have spare capacity. When teaching, I ask students to think on the basis of reading the topic fully, and then talk about their own problem-solving methods. Li Xiang is a clever student in our class. He stood up and said, "First use 20×22 to calculate the distance that the antelope runs is 440m, then use 20×3 1 to calculate the distance that the leopard runs is 620m, and 620-440 =180m, 180 > 158. At this time, Liu Zizheng's little hand was still not put down. I asked, "Do you have any other methods?" The child said confidently, "First, use 3 1-22 = 9 meters to calculate that the leopard runs 9 meters more than the antelope every second, and then use 20×9= 180 meters, 180 > 150, so that the leopard can catch up with the antelope in 20 seconds." No sooner had Liu Zizheng finished speaking than Wu stood up and said, "I have another way to solve this problem. The first two steps are the same as Li's thought. First calculate the distance between antelope and leopard in 20 seconds, then 440 meters plus antelope 150 meters equals 590 meters, and the remaining leopard runs 620 meters, then the leopard can catch up with antelope. "I really didn't expect the children to talk so much about solving problems. I couldn't help but give a thumbs-up and say," You are really great! The teacher only thought of 1 solutions, but you thought of three. It seems that there is still strength in uniting! "

To tell the truth, when I was looking at this question before class, I only thought about using the speed difference between the two to get the catch-up distance (the method Liu Zizheng said), and I didn't think much. As soon as the children said it, I realized that there were so many solutions! It seems right to encourage children to solve problems in various ways. The children gave me another wonderful lesson!