Teaching objectives:

1. Teach students to observe the line chart, find out the quantitative relationship between information and questions, and calculate correctly.

2. Two pieces of information and 1 question can be represented by a line chart. Further understand the relationship between addition and subtraction.

3. Make students gradually develop the habit of analyzing and solving problems with their brains.

Teaching focus:

Teach students how to observe and how to draw.

Teaching difficulties:

How to accurately express "more", "much more", "less" and "much less" in line segment diagram?

Teaching preparation: courseware

First, stimulate interest and introduce dialogue before class.

Teacher: Students, are you happy that there are so many teachers in class with us today? Say hello to the teacher. (Good teacher) Please sit down.

The teacher found that you were "dizzy" when solving math problems. Therefore, in this class, the teacher invited our good helper-line diagram to help everyone learn the math problem of "how much to compare". The teacher hopes that through the study of this class, the students' little heads will become clear and smarter. Can you do it? (Show the topic) Please read the topic.

Second, observe the line segment diagram.

First of all, the teacher will test everyone to see who has the most careful eyes and who has the best mouth to talk.

1, courseware shows:

Teacher: Please look at the line diagram. Who can tell us how you observe it?

1: I observed the first line segment and found the message 1. There are 24 people in the art troupe.

Health 2: I observed the back part of the second line segment and found data 2. The music group has 40 more people than the art group. It can also be said that the art group has 40 fewer people than the music group.

Teacher: Ask the teacher what?

S3: I observed the second line and found this question: How many people are there in the music group?

Teacher: Who will tell us again how you observe?

Health 4: …

Teacher: After collecting the information and questions, let's make a second observation. To solve the problem of how many people are in the music group, which line segment should we mainly observe? Why?

Student: To solve this problem, we mainly observe the second line segment, because there are as many people in the art group as in the front part of the music group. If we add 24 and 40 together, it is the number of people in the music group, which is the problem we have to solve, so we use addition to calculate.

Teacher: How to calculate continuously?

Student: 24+40=64 (person) A: There are 64 people in the music group.

Teacher: Students are really good at observing and talking. Then try another question.

2. Show the courseware:

Teacher: What mathematical information and questions can be collected by observing the line diagram?

Health 1: I observed the first line segment and found the message 1, with 65kg of cabbage; I observed the back part of the first line segment and found message 2: Chinese cabbage is more than eggplant 10 kg, or eggplant is less than Chinese cabbage 10 kg.

Health 2: I observed the second line segment and found the question: How many kilograms of eggplant is there?

Teacher: After collecting the information and questions, let's make a second observation. To solve the problem of how many kilograms of eggplant is, which line segment should we mainly observe? Why?

Health: To solve this problem, we should mainly observe the first line segment, because there are as many front parts of Chinese cabbage as eggplant. There are still 65 kilograms removed 10 kilograms of eggplant. How many kilograms? This is a problem that we must solve.

Teacher: So how to calculate it?

Student: Calculate by subtraction.

Teacher: How to calculate continuously?

Health: 65- 10=55 (kg) A: Eggplant has 55 kg.

4. Summarize the methods of observing the line segment diagram.

Teacher: Through the observation just now, who can tell us how to observe the line graph?

Health 1: Make clear what each line segment represents.

Health 2: mainly observe a long line segment and list formulas according to the relationship between information and problems.

Teacher: It seems that the students in our class have mastered the method of observing line segments well. Can you draw a line graph according to the information and questions?

Third, draw a line segment.

1, courseware shows:

Show the questions first and watch them together.

Teacher: Who will collect the math information?

Health: Message 1: A bag of biscuits 8 yuan,

Message 2: A box of cakes is more expensive than a bag of biscuits 10 yuan.

Teacher: What is the problem to be solved?

Health: How much is a box of cakes?

Teacher: According to the mathematical data and questions, how many line segments do you think are appropriate?

Health: Two. Because the price of biscuits is compared with the price of cakes. (Compare two quantities)

Teacher: Which information should I draw first?

Health: ...

Teacher: Actually, you can draw any one first, but it must conform to the meaning of the question.

If the teacher now uses a line segment to indicate that a bag of biscuits has 8 yuan, please think about how to draw a line segment to indicate the price of the cake. Give students some time to think and then ask questions. )

Health: Draw a line segment below which is longer than above.

Teacher: Why do you want to draw it longer?

Health: Because of a bag of biscuits, 8 yuan is famous, and cakes are more expensive than biscuits 10 yuan.

Teacher: What should I do after drawing the second line segment?

Health: Divide this line segment representing the cake into two parts with a dotted line. The second half means that cakes are more expensive than cookies 10 yuan, and the first half means that there are as many cakes as cookies, which is the problem we have to solve.

Teacher: Who can tell us how to draw it just now?

Now, please ask xx to take you to check. Does our line drawing meet the meaning of the question?

Health: …

2. The courseware shows the second drawing method and gives a brief introduction.

Teacher: Actually, we can also draw this line segment representing the cake first. Look at the screen. …

3. Courseware demonstration: (right)

Teacher: Read the questions in class.

Teacher: Who will collect the math information?

Health: information 1: 25 story books; Message 2: More than comics 12.

Teacher: What is the problem to be solved?

Health: How many comic books are there?

Teacher: Just now, the students taught the teacher to draw line drawings, and the teacher was particularly excited. Now I draw such a line chart according to the information and problems in this question. Ask the teacher to help you judge?

Health: No.

Teacher: Huh? What's the matter?

Health: The line segment representing comics is short.

Teacher: Why do you say that this line segment representing comic books is short?

Health: Because the information tells us that there are more story books than comics 12, not comics 12. Now the line drawn here is 12 cartoon.

Teacher: You observe very carefully. How should this line segment of the cartoon be drawn? How long is this picture?

Health: It should be shorter than this line in the story book. (The teacher's courseware demonstrates the correct drawing method)

Teacher: Let the students talk about painting softly and watch the teacher's demonstration.

Teacher: Did the teacher draw it correctly this time?

Health: That's right.

Teacher: The students in our class are really amazing. They helped the teacher correct his mistakes. Thanks again!

5. Summarize the method of drawing line segments.

Teacher: Through the study just now, who will tell me how to draw line drawings? What should I pay attention to when drawing line drawings?

Health 1: collect mathematical data and questions first; Determine whether to draw a line segment for analysis or two line segments for analysis; ? If you draw two line segments for analysis, you can draw any quantity first, but it must conform to the meaning of the question.

Health 2: Pay attention when drawing line segments: the left ends of the two line segments should be aligned; ? Don't draw short lines for large numbers, and don't draw long lines for small numbers; When comparing two quantities, it is necessary to correctly judge whether it is less or much less; Is it much or much more?

Fourth, consolidate and expand.

Teacher: It seems that the students in our class can already observe the line chart. I can also draw a line graph. Let the students draw a line graph to solve the following problems, ok?

1, show the answer sheet, students draw line drawings independently to solve problems, and teachers patrol for guidance.

2. Communicate with the whole class.

Ask students with different drawing methods to show their homework and communicate how they are drawn and according to what formula. Teachers guide students to make judgments and evaluations, and analyze and correct mistakes.

Verb (abbreviation for verb) class summary.

Teacher: What progress have you made through today's study?

Health: ...

Teacher: The students in this class are doing very well. Their little heads become clearer, smarter and more talkative. That's great.