This lesson is the teaching content on pages 56~57 of Unit 7 "Arithmetic Law" in the second volume of Grade Four Mathematics in the national curriculum standard. It is taught on the basis that students have learned the laws of multiplication and distribution. Through the teaching of this course, students can master the characteristics of constructing simple arithmetic problems by multiplication and division, learn to use multiplication and division to make simple calculations, and promote the flexibility of computational thinking; At the same time, let students learn to use estimation methods to judge the rationality of calculation results, and actively use laws to solve practical problems in combination with practical problems; In this course, we can feel the universal applicability of mathematical laws, further understand the relationship between mathematics and life, and gain a sense of pleasure and success in using mathematical laws to improve calculation efficiency, improve learning interest and enhance self-confidence.

Teaching process:

Process 1: Basic exercises

Process 2: Feedback Communication Paragraph 1: Basic exercises

Process 3: Scenario Introduction

Process 4: Algorithm Exploration

Process 5: Algorithm communication

Process 6: Feedback communication

Flow 7: Algorithm Comparison Paragraph 2: Algorithm Exploration

Process 8: Summarize the transition

Process 9: Give it a try.

Process 10: Try to communicate.

Process 1 1: Summary

Process 12: consider doing part 2 and part 4.

Process 13: communication, thinking and action.

Process 14: Thinking and Doing 5 Paragraph 3: Consolidate exercises and practice applications.

Process 15: Communication, Thinking and Action 5

Process 16: Class Summary Paragraph 4: Class Summary

The first paragraph: basic exercises

Process 1: Basic exercises

Teacher: Students, yesterday we discussed a very important law in multiplication, multiplication and division. Do you remember? We watch exercises together.

The courseware shows the basic exercises: fill in the appropriate numbers in □ and the operation symbols in ○.

(40 + 7)× 12 = □ ○ □ ○ □ ○ □

29 × 56 + 56 × 3 1 =(□ + □ )○ □

Teacher: These fill-in-the-blank questions. Please write it in your notebook and then talk to each other at the same table. What is the basis for you to fill in? (pause)

Process 2: Feedback communication

The courseware shows the answers to the above questions: (40+7 )×12 = 40×12+7×12.

29 × 56 + 56 × 3 1 =(29 + 3 1 )× 56

Teacher: Let's look at the answer. Is that how students fill it out? Yes, according to the multiplication and division method, the sum of two numbers is multiplied by a number, that is to say, these two numbers are multiplied by this number respectively, and then the two products are added, which can be expressed in letters as: (a+b)×c= a×c+ b×c (courseware is presented at the same time).

The second paragraph: algorithm exploration

Process 3: Scenario Introduction

Courseware display theme map: (sketch)

Teacher: Let's keep looking. What information do you learn from the picture? What problem do you want us to solve? According to the information provided in the picture, how to present it? Please watch carefully, think about it and list the formulas in your notebook. (pause)

Process 4: Algorithm Exploration

Teacher: How much do you want to spend on a * * *? We can put it this way: the formula of courseware presentation is 32 × 102.

Please estimate the product of 32 times 102 first, then work it out in your notebook, and then tell your deskmate how you worked it out. (pause)