Who has been on the phone for a long time? What is the lesson plan of Beijing Normal University?

Category solution

Teaching plan design

design instruction

The content of this lesson is fractional division in which the divisor is a decimal. It is taught on the basis that students master fractional division with divisor as integer. In order to respect students' existing knowledge and experience and protect students' enthusiasm for inquiry, the teaching design of this section has the following characteristics:

1. Create a situation to encourage students to ask questions and solve problems.

Through the life situation of two children talking on the phone, this paper studies who talks on the phone for a long time, and guides students to actively participate, calculate, cooperate and reflect, so that students can feel that mathematics comes from life and further understand the close relationship between mathematics and real life.

2. Make full use of students' life experience and existing knowledge to guide students to explore the calculation method of fractional division.

Let students actively explore the calculation method of fractional division with divisor as decimal, and infiltrate the mathematical thought of reduction. Guide students to think from different angles, get inspiration from mutual communication, find problems and solve problems in the process of inquiry.

For example, why does the divisor decide how many times the dividend and divisor are enlarged? This will not only help students understand the calculation method of fractional division, but also improve their ability to find and solve problems.

Preparation before class

1 (1) class prepares PPT courseware. Who calls for a long time?

teaching process

1 (1) who talks on the phone for a long time?

Create situations and stimulate the introduction of interest

1, the courseware shows the situation diagram of the textbook, guiding students to find mathematical information and find mathematical problems.

Guide the students to observe Xiaoxiao and naughty phone calls, and make domestic long-distance calls with Xiaoxiao. Every point in 0.3 yuan costs * * * 5. 1 yuan; Naughty bag international calls, 7.2 yuan per minute, 54 yuan per minute.

2. Ask a question: Who calls for a long time?

Design intention: Show students the situation, let them ask questions and stimulate their interest in learning.

Explore algorithms and solve problems

1, estimated. (first estimate who has been on the phone for a long time)

(1) Discuss in groups how you estimate.

(2) Report the estimation process in groups.

Student report:

(1) The international call per minute in 7.2 yuan is about 20 times that in 0.3 yuan. If Shao Xiao and the naughty boy talk at the same time, the call fee of the naughty boy should be 20 times that of Shao Xiao, but 54 yuan is about 5.65438+ 10 times that of 0 yuan, so Shao Xiao talks for a long time.

②5. 1 has about a dozen 0.3, so it takes more than ten minutes to make a phone call with a smile, and there is no 7.2 of 10 in 54, so the naughty phone call time is definitely less than 10, so it takes a long time to make a phone call with a smile.

2, column type and calculation.

Teacher: To ask who has been on the phone for a long time is to find out the minutes of laughing and naughty phone calls respectively. How to list them?

Students understand the meaning of the question and list the formulas: 5.1÷ 0.3,54 ÷ 7.2.

3. Independent query and communication algorithm.

(1) Students' independent calculation 5. 1÷0.3.

Thinking: calculate with the method you think is reasonable; Can fractional division with decimal divisor be converted into division with integer divisor? How to transform? What law is applicable?

(2) Organize students to communicate with each other.

Method 1: Turn 0.3 yuan into 3 angles, and 5. 1 yuan into 5 1 angle, which becomes 5 1÷3, which is the division of integers we learned before, and 5 1 ÷ 3 = 17 (point).

Method 2: Using the properties of constant quotient, the divisor 0.3 is changed into an integer and expanded to 10 times. To keep the quotient unchanged, the dividend should be expanded by 10 times to 5 1, and the dividend changes with the divisor. 5 1 ÷ 3 = 17 (point).

Method 3: Use vertical calculation.

(3) Understand the arithmetic of vertical calculation.

(1) Instruct students to circle the decimal orthographic diagram on page 7 of the textbook, and understand that 0.3 is three 0. 1, so 5. 1 is 5 1. It depends on how many 0.3 can be circled by 5. 1, that is, how many 3 can be circled by 5 1.

(2) Discuss how to calculate the fractional division with divisor vertical to decimal.

The teacher pointed out that if the divisor is expanded to 10 times, it will become an integer. In order to keep the quotient unchanged, the dividend should also be expanded to 10 times. Then demonstrate the vertical writing. (3) Guide students to check.

(4) Summarize the calculation methods and report by name:

① Enlarge the divisor to make it an integer.

(2) When the divisor is expanded several times, the dividend should also be expanded by the same multiple.

(3) Division by divisor is an integer.

4. Calculate 54÷7.2 and ask students to complete it independently.

Tip: How should the dividend change after the divisor 7.2 is converted into an integer?

5. Compare who has been on the phone for a long time.

Design intention: Let students use their existing knowledge and experience to explore the calculation method of fractional division with divisor as decimal. Different students think from different angles and solve problems in different ways. After students think independently, give them some time to communicate, inspire each other and learn from each other. This not only helps students to understand the calculation method, but also helps to improve their problem-solving ability.

Consolidation exercise

1. Complete the two questions "Practice and Practice" on page 8 of the textbook.

2. Complete the 7 questions "Practice and Practice" on page 9 of the textbook.

3. Use vertical calculation.

35÷0.5=0.768÷ 1.6=

37. 1÷0.53= 12.6÷0.3=

Design intention: arrange targeted exercises in practice to further consolidate new knowledge.

Classroom summary

What did you learn from this course? What problem do you want to remind everyone?

Assign homework.

Textbook Exercise and Practice, page 9, questions 4 and 8.