Design of "multiplication formula" exercise in the first volume of grade four

This course is mainly about the written calculation of multiplying three digits by two digits. Students study on the basis of multiplying three digits by one digit and multiplying two digits by two digits. In order to make students better master the written calculation theory and general method, and transfer the general method to the multiplication of multiple digits to meet the requirements of students at different levels, three-level exercises are designed, which embodies the hierarchy of classroom exercises.

First, basic exercises

1, compare and see who did it (screen display)

2 3 5 3 1 2 5 8 3 1 3 7

× 1 4 × 3 6 × 2 8 × 7 5

Let each student do it independently, and deepen the understanding of the meaning of multiplication when students solve new problems with old knowledge. Improve the skills of writing multiplication and form a good cognitive structure of multiplication. )

2. Write down the following questions and check them with a calculator.

87×23 1= 358×4 1= 356×86= 75×820=

Ask the students to reflect on the basis of independent trial and comparison, and understand that when the column is vertical, it is easier to write three digits on the top row and two digits on the bottom row. )

Third, variant exercises

Name the following mistakes in calculation and correct them:

1 3 4 1 5 2 2 4 6

× 1 6 × 2 3 × 3 4

8 0 4 1 5 6 9 6 4

1 3 4 1 0 4 6 3 8

9 3 8 1 1 9 6 7 3 4 4

(In the form of correcting mistakes, correct the mistakes that students are prone to in the calculation process and improve the correct rate of multiplication calculation. When practicing, let the students observe each vertical position first, say what is wrong, and then correct it. )

Second, using multiplication to solve practical problems

1. The school is going to distribute exercise books to class 15, and each class 144 copies. The whole school needs to keep 40 copies. How many exercise books should schools buy?

2. Vegetable farmers grow all kinds of vegetables. The prices of some vegetables and the number of pots sold are as follows:

diversification

pepper

tomato

Pocket pumpkin

Unit price/yuan

12

14

15

Number of cans sold/cans

382

135

148

(1) How much is each vegetable?

(2) What is the income of a * * *?

(3) What other math problems did you find from the table?

In practice, by solving these specific problems, students can deepen their understanding of the meaning of multiplication, form the calculation skills of multiplying three digits by two digits, feel the application value of what they have learned and enhance their application consciousness. )