Teaching objectives:

1. Understand the meaning of graphic area with specific examples and screen activities.

2. Through the comparison process of two graphic areas, experience the diversity of comparison strategies, exercise mathematical thinking ability, develop the concept of space, and stimulate the interest in further study and exploration.

3. Infiltrate the strategic awareness of solving problems.

Teaching emphasis: combine specific examples and screen activities to understand the meaning of graphic areas.

Teaching difficulties:

The formation of the concept of 1. area.

2. Experience the diversity of comparison strategies by comparing the sizes of two graphs.

Teaching preparation: small blackboard, rectangle, square, triangle, round card, coin, schoolbag, colored pen, etc.

Teaching process:

First, create a situation

(Design the game of "I say you point": the teacher says the students point, and see who responds fastest and can point right. )

Teacher: Just now we played a game together, which also included math knowledge. Who can guess what you ordered in the game? (student exchange. )

Teacher: Actually, you mean their "faces". (Write it on the blackboard. )

Intention: Teachers set up game situations, and students initially perceive the surface of objects or graphics with their eyes, hands and other senses, which fully mobilized students' learning enthusiasm.

Second, explore the size of the perception area.

1. Touch.

Teacher: Now, please touch the face of your hand, the face of your math book, the desk … touch the face of the objects around you. (health activities. )

Teacher: Who can tell me what you found? (Health report, the teacher writes on the blackboard. )

Teacher: Through the activities just now, what we can touch is the "surface" of the object. Some "surfaces" are flat, some are curved, some are big and some are small.

Teacher: Can you name the size of an object's surface in mathematical language?

(Students speak freely. )

Teacher: Everyone is right. Mathematically, we call "the size of the surface of an object" the area of the object. (Blackboard: area. )

Intention: Make use of the things around students, let them contact and talk about which area is large and which area is small, thus naturally leading to the significance of area in mathematics.

2. Compare the sizes of plane graphics.

Group activity: Draw the outlines of rectangular, square, triangular and circular cards on paper, and then paint the drawn figures with your favorite colors. Then ask the students to say, which is the biggest figure drawn by their group? Which is the smallest?

Teacher: What figure did you draw just now?

Health: There are rectangles, squares and triangles. ...

Teacher: What you draw are all called plane figures. What do you find through sketching and coloring?

Health: There are large and small floor plans.

Teacher: So what is the size of the plane figure? (blackboard writing: the size of the plane figure. )

Health: area.

Intention: To mobilize all kinds of senses in painting, so that students can initially perceive the size of plane graphics and enrich their perceptual knowledge of the region.

3. Summarize the meaning of "area".

Teacher: Now, everyone knows what "area" means. This is the new content we are going to learn today. (Write on the blackboard: What is the area? ) Tell your deskmate what the area is in simple language. (Students summarize. )

Teacher: Let's see what our math experts say. Courseware shows that the size of the surface or plane figure of an object is their area. )

Teacher: What you said is very close to what the experts said. The students' generalization ability is really strong.

4. The difference between area and perimeter.

Teacher: From the painting and painting just now, do you think the circumference and area are the same thing? What's the difference between them?

Health: perimeter is the total length of the edge line on the surface of an object, while area refers to the size of the surface of the object.

Intention: After students fully perceive and form appearances, teachers sublimate knowledge to a rational level, clarify the essential meaning of knowledge, summarize the essential attributes of things, and extend these essential attributes to all similar things, thus forming the concept of area. Through coloring activities, students can feel that the size of a plane figure is its area, which can be distinguished from the perimeter of the surface of an object. Similarly, consolidating perimeter and area are two different concepts.

Third, comparative exploration methods.

1. A set of numbers is displayed on the small blackboard.

Teacher: Now look at these two figures on the blackboard. Who can use the word "area" to compare the sizes of these two figures? Which one do you think has the larger area?

Health: The area of a square is larger than that of a rectangle.

Teacher: How do you know the size of these two numbers?

Health: I can see it with my eyes.

Teacher: Look with your eyes and compare the areas of these two figures. This method is called observation. (blackboard writing: observation. )

2. Start exploring.

Teacher: Please take out the rectangular and square cards. You can guess which graphic area is large first, and use the tools around you to prove your idea as needed. Let's see who has come up with many ways. (health activities. )

Teacher: Now look at these two figures with your eyes. Can you tell who is older and who is younger?

Health: No.

Teacher: Then what should we do? Please use the strength of the team to solve this problem, ok? Let's discuss how to compare the areas of these two planes. Please choose a favorite method in your group and show it to the class. (Students use the methods of cutting and spelling, counting squares, putting squares, putting coins, etc. And report. )

Teacher: Everyone speaks very well. Some groups say that they are compared by overlapping method. (Blackboard: Overlapping Method) Some people say that they should be overlapped, and then the more they are cut and put together. By contrast, this is "cutting and spelling". (blackboard writing: cutting and spelling) Some people say that a pendulum is placed with the same coin to see which figure has more coins and which figure is bigger. This is called "spelling". Some groups think that by drawing squares with the same size on these two figures, we can know who is big and who is small by counting the squares. This is the method of "counting squares". (blackboard writing: count the squares. )

……

Teacher: People think in many ways. Because of the time, today we will learn the method of "arranging" first. Just now, that classmate said to put it in coins. What other graphics can I use to put it?