Teaching objectives:

1, so that students can further master the oral calculation of hundreds of times, dozens of times (without carrying) and hundreds of times (without carrying) and the estimation of hundreds of times of numbers close to integer ten, further master the written calculation of multiplying three digits by two digits, and can apply these calculations to solve some practical problems.

2. Make students have a deeper understanding of letters expressing numbers, and further improve their ability to express quantitative relations and calculation formulas in practical problems with letters, so as to find out the numerical values of letters and further develop the sense of symbols.

3. Make students further understand the changing law of product and the application of constant quotient law in calculation, and make a simple calculation.

Teaching emphases and difficulties:

The application of the invariant law of product-variable quotient in calculation and the understanding of letters representing numbers.

Teaching resources:

Small blackboard, etc.

Teaching process:

First, create a situation

1, Dialogue: Students, the term will be over in a blink of an eye. After studying for a semester, your knowledge must be enriched! Can you review the contents of this semester's study and your own study?

2. Please fill in the form on page 108 of this book independently, and then communicate with the group about your study.

3. Group communication.

4. Classroom communication: What is the best content you have learned?

What are you most interested in?

What difficulties do you find?

Any suggestions for the teacher?

5. Discard the topic: Today, let's review the calculation of "multiplication and division" and "using letters to represent numbers".

Second, review the calculation of multiplication and division.

1, review 1 questions.

(1) Students independently choose a group of questions to calculate, and organize comparison after calculation;

(2) Sort out the written calculation method of multiplying three digits by two digits and the simple written calculation method of multiplication and division to consolidate the understanding of the changing law of product and the law of constant quotient.

2. Organize to review the second question.

Let students solve practical problems, further understand the significance and methods of multiplication estimation, communicate the connection between estimation methods and written calculation methods, and improve their calculation ability.

3. Organize to review the third question.

(1) Let the students carefully observe the characteristics of each question and talk about what method they plan to use for calculation.

(2) Students complete the calculation independently;

(3) collective inspection, correct mistakes and explain the reasons.

Third, review the numbers represented by letters.

Organize and review question 4:

Let the students fill it out independently first, and then communicate their thinking process. Among them, the question (1) should encourage students to list different formulas, and the question (2) should prompt the writing standard for finding letter sub-values.

Fourth, the class summary

What did you buy today? Do you have any difficulties?