course content

The content of page 4 1 of the first volume of the third grade mathematics in the compulsory education curriculum standard experimental textbook published by People's Education Press.

Teaching objectives

1. Let students feel, experience and explore the perimeter of the figure in operation and understand the meaning of the perimeter.

2. Cultivate students' sense of cooperation in practical activities.

3. Stimulate students' interest in exploring questions in learning activities and cultivate students' awareness of inquiry.

Teaching preparation

Teachers prepare: leaves, rectangular, square, triangular and diamond cards, round clock face cards, flag cards, butterfly specimens, etc.

Students prepare: rulers, lines, soft rulers, leaves, rectangles, squares, triangles, standard five-pointed stars, circular cards, etc.

teaching process

First, skillfully use the word "Zhou" to guide the exploration of the meaning of "perimeter"

(A) the introduction of dialogue

At the beginning of the class, the teacher flexibly introduced the word "week" and combined it into: week.

Teacher: Do you know what the word "Zhou" means?

The students' answers are: one week, one week; Around, in a circle; Person's surname; Wait a minute.

(2) Reveal the topic

Teacher: The knowledge we are going to learn in this class is closely related to the word "week".

The teacher put the leaves, flag cards, clock cards, butterfly specimens and triangle, square, diamond and standard five-pointed star cards on the blackboard. )

Exposure: What we want to study is the "perimeter" of these figures.

Supplementary blackboard writing: Dragon (complete the title "Perimeter").

[Ingenious introduction awakens students' first cognitive experience of "circumference" in their brains, stimulates students' bold speculation, reasoning and active exploration of practice on this basis, and reflects students' dominant position in the learning process. ]

(3) Speculation and exploration

Teacher: Guess, the perimeter of these figures may be related to the meaning of the word "Zhou".

Health speculation: related to the meaning of "left and right" and "around"

Teacher: So, according to everyone's understanding, the perimeter of a leaf should refer to its ...? Ask students to point out in kind.

(D) inductive understanding

Teacher: These figures are of different sizes and shapes, but they all have their own perimeters. So, what does "periphery" mean? Can you express it in words? Give it a try!

Health 1: For example, the circumference of a triangle is the length of its three sides.

Health 2: Perimeter is the sum of the lengths of all sides of a figure.

Health 3: Like a circle, it has no straight edge, and its circumference is the length of its week.

……

Read the book and compare the description of the perimeter in the textbook to understand that "the length of a closed figure is the perimeter of the figure" in communication.

Let the students try to express their understanding and knowledge of the circumference. Students have to go through the process of independently summarizing and expressing their fragmentary representations of graphic perimeter, which is conducive to cultivating students' logical thinking and expressive ability. ]

Second, operate activities and independently experience the meaning of "perimeter"

(A) the introduction of dialogue

Teacher: Is there any way to let us know the perimeter of these figures?

Health: You can test it.

Teacher: Are you confident to measure the perimeter of the above figure?

Practice leads to true knowledge, and students can further understand the meaning of perimeter only through operation, which also provides students with new exploration and development space. ]

(2) Permeability requirements

Teacher: The teacher has prepared the following "Smart Hand Test Sheet" for everyone. Let's take a look first.

The circumference of a rectangle is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

The perimeter of a square is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

The perimeter of the leaves _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

The circumference of a circle is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

The circumference of a triangle is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Head circumference _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

The circumference of the pentagram is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Waist circumference _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Bust _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Teacher's guidance: There are many activities here that are difficult for one person to complete. You can find a partner to complete these activities together. Make full use of your existing learning tools and measuring tools to complete these activities and record data. Let's compare which partners cooperate well and accomplish more!

[In the operation activities that these students have to find a partner to complete, students naturally realize the necessity of cooperation, and the sense of cooperation is also cultivated invisibly. ]

Third, exchange summaries and show students' achievements.

Teacher: You have measured and explored the perimeter of so many figures. What good methods have you got? Communicate with everyone.

Health 1: I found that there are a lot of figure perimeters. When measuring, it is not necessary to measure the length of all sides, but only a part. For example, the five-pointed star, whose ten sides are all equal in length, only needs to measure the length of one side and add up ten identical numbers.

Health 2: The circumference of a rectangle, you don't need to measure all the lengths of four sides, just measure one long side and one short side to know the other sides, and the opposite sides of the rectangle are equal.

Health 3: I find it difficult to measure the circumference of a circle, not with a ruler. We wound the wire once, only to find that with a little force, the wire straightened and it was difficult to measure.

Health 4: There is a way. You can fold it in half, so that you can circle the length of its semicircle and multiply it by 2.

Health 5: It can also be folded in half, so that the curve to be measured is shorter. Measure the length of this curve and multiply it by 4.

Health 6: When I measured my waistline, I found that I measured the thickness of clothes from the outside, which was inaccurate. It should be measured against my stomach.

Health 7: I know the perimeter of a graph, and I can also measure the perimeter of many graphs.

……

Fourth, summarize the incentive measures to cultivate students' confidence in independent inquiry.

Teacher's summary: In this class, we not only know the circumference of a figure, but more importantly, when we encounter difficulties, we give full play to our wisdom and explore a lot of important mathematical knowledge from these activities. It is not easy! This is inseparable from the unity of your two partners. Congratulations! I hope you can give full play to your ability of being good at discovery and exploration in your future study!

[The summary is vivid and concrete, which not only pays attention to the knowledge focus of this lesson, but also pays attention to the students' emotional experience, which effectively stimulates students' confidence in learning mathematics well and embodies the new concept of curriculum standards. ]

Instruction design description

This lesson focuses on students' knowledge and understanding of "perimeter", creating an activity space for students to fully guess and explore, allowing students to boldly imagine, speculate, express and communicate on the basis of existing knowledge and experience, and gradually explore the meaning of "perimeter", and then experience and understand the practical significance of perimeter in a large number of operational activities, so that students' understanding of perimeter can be sublimated in practice and they can make future "perimeter calculation". It fully highlights students' dominant position in learning and effectively cultivates students' interest in learning mathematics.

Comment and analysis

The teaching design of this lesson "Understanding Perimeter" is novel and unique, which is a bold attempt of concept teaching, embodies a new teaching concept and gives people a refreshing feeling. To sum up, there are the following characteristics.

1. Introduce the new lesson "new". The clever use of the word "Zhou" in the new course makes students feel that "Chinese character knowledge" can also be used in mathematics class, which stimulates students' interest and strengthens the integration between disciplines; At the same time, make effective use of students' cognitive experience to lay the foundation for understanding the meaning of "perimeter".

2. The activity design is "new". In the process of letting students experience the meaning of perimeter independently, the teacher designed an open measurement activity, including measuring the perimeter of regular graphics, such as rectangles and squares; Measuring the perimeter with irregular patterns, such as the perimeter of leaves; There are also measurement activities such as head circumference and waist circumference. In the whole activity, the teacher completely let go, so that every measurement activity is a brand-new exploration activity that needs brains for students, creating more exploration space for students.

3. The learning method is "new". In this lesson, autonomous learning runs through the whole learning activity: students independently understand the meaning of "perimeter", independently measure the perimeter of the figure, and explore and cooperate independently in the measurement activity, and enjoy learning. Students' autonomous learning consciousness has been effectively cultivated in learning activities.