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? Teacher: Now I ask you to prove your point with actions. Let the students make a pendulum with the materials provided in their schoolbags to see which figure has the largest area. Requirements: 4 people cooperate, put a pendulum, stick a stick. When publishing, one graphic is next to another. Compare the sizes of two pictures after pasting.

(Students show communication. )

Teacher: What did you find during the assembly of the pendulum?

Teacher: Through the activities put together, you observe the works of these groups and compare them. Which number is more scientific and accurate? Why?

Health: It's best to put it in a square. There is nothing, and there is no gap. ...

3. summary.

Teacher: Through experiments, we know that square placement is a more scientific method. Then in practical application, we can compare the size of the graphic area by drawing squares and counting squares. In daily life, we should think more about some methods when solving problems and choose which method is more scientific.

Intention: Comparing the size of the area is divided into two levels: one is to observe with eyes, and the other is to guide students to compare the size with tools when they can't observe and compare with eyes. In group cooperation, students independently explore a variety of methods to compare the size of the area, from easy to difficult, close to the area where students' knowledge develops. Let students experience the diversity of strategies in comparing regional sizes, penetrate the strategic awareness of solving problems, and reflect the autonomy of the learning process. Let students experience the whole process of knowledge formation, deepen the understanding of the meaning of area, and cultivate the ability of analysis and comparison and the sense of cooperation.

Fourth, practical application, consolidation and extension.

Teacher: Now please use what you have learned to solve some simple problems.

1. Finish after class 1~3 questions.

2. Complete the "Draw a Picture" in the book.

Verb (abbreviation of verb) abstract

Teacher: What have you gained from this class?

……

Reflection:

This course has a lot of students' independent exploration process, and the teaching process better embodies the concept of "let students experience the whole process of knowledge formation" in the new curriculum.

1. Learn mathematics in a rich life background, strengthen perception and establish concepts.

This lesson belongs to the teaching of the concept of area. The concept of area is abstract, which will be difficult for students to understand. In order to let students better understand and master the abstract concept of "area", I start with life, let students perceive the size of an object through the activities of looking and touching, reveal the area of an object through the comparison of the surface size of the object, and let students connect the abstract concept of area with concrete examples in life to deepen their understanding of the area. In this way, the layers are deep and interlocking, and students unconsciously understand the meaning of area. On this basis, the essential characteristics of the concept are revealed by grasping the key words, so that students can clearly understand the essential attributes and significance of the new concept. This not only raises perceptual knowledge to rational knowledge, but also rises from knowing why to knowing why. At the same time, students develop their intelligence, improve their quality and embody new teaching ideas in the process of learning.

2. Create opportunities for practical activities, so that students can experience the whole process of knowledge formation.

In the process of exploring and comparing the sizes of the two figures, a space for students to engage in mathematics learning activities and exchange is created. Students first discuss the methods of comparison, and then verify their guesses through practice and operation. Students choose different methods to compare through multi-angle and multi-faceted thinking such as cutting and spelling, counting squares and overlapping. Teachers timely guide, so that every student has the opportunity to express their ideas, so that inquiry learning can be implemented. In this way, students fully and actively participate in the learning process, so that different students can get different development in mathematics learning. In practice, students have experienced the whole process of knowledge formation, deepened their understanding of the meaning of area, and cultivated their analytical and comparative abilities and cooperative consciousness. Infiltrate the strategic consciousness of solving problems to a certain extent.