The content of the lecture is the objects and symmetrical figures observed in Unit 5 of the first volume of the second grade of the compulsory education curriculum standard experimental textbook "Mathematics". These contents are the necessary basis for learning the knowledge of space and graphics, and play an important role in helping students to establish the concept of space and cultivate their spatial imagination. Teaching materials are based on students' life experience, position and knowledge, and are taught with the help of real objects in life and students' operational activities.

Based on the above understanding, I have determined the teaching objectives of this course as follows:

1. Knowledge goal: Through practical operation, we can initially understand that the shapes of objects seen from different angles are different, and learn to correctly judge the position of observers according to the shapes seen.

By understanding the phenomenon of axial symmetry, we can find and draw the axis of symmetry correctly.

2. Ability goal: cultivate students' observation ability, comparative ability and practical ability, develop students' initial concept of space, and infiltrate dialectical materialism that mathematics comes from life and is used in life.

3. Emotional goal: to stimulate students' enthusiasm for learning through inquiry activities and cultivate students' ability to explore actively; Let students feel the beauty of symmetrical figures and learn to appreciate the beauty of mathematics.

Key points and difficulties:

The key point of this lesson is: learn to correctly judge the position of the observer according to the shape you see. Knowing the symmetry phenomenon, we can find and draw the symmetry axis correctly.

The difficulty of this lesson is to understand the symmetry phenomenon and find the symmetry axis.

Second, oral teaching methods

1. Curriculum Standard of Situational Teaching Method points out that mathematics teaching activities must be based on students' cognitive development level and existing knowledge and experience. Therefore, the creation of scenes should be based on students' life experience and knowledge background. At the beginning of a new lesson, observing toy dogs and guessing activities with games can stimulate students' interest in learning, so as to review old knowledge and prepare for new knowledge. Then design a scene to draw a puppy, and let the students draw a puppy by hand. At first, they felt that the position was different and the shape of the puppy was different. Then, by designing the life scene of distributing gifts, students are stimulated to explore the learning climax of symmetrical graphics.

2. The demonstration method makes full use of visual images to promote students to rise from perceptual knowledge to rational knowledge. When teaching symmetrical graphics, students can get perceptual knowledge by dynamically demonstrating the completely overlapped pictures of symmetrical graphics after being folded in half by computer. Then use computer to demonstrate the symmetrical things in life, let students feel the beauty of symmetry, learn to appreciate the beauty of mathematics, and infiltrate the idea that mathematics comes from life and is used in life.

3. When using the discovery method to teach symmetrical figures, the teacher sends a group of pictures to the study group to guide the students to observe carefully, fold and draw a picture, and classify them on the basis of observation and discovery. When students separate symmetrical and asymmetrical figures, guide them to observe and discover again. The role of teachers is to organize discovery activities, pay attention to students in the activities, and let students learn new knowledge and experience the exploration process.

Third, theoretical study.

Curriculum standards point out that effective mathematics learning activities can not only rely on imitation and memory, but also practical, independent exploration and cooperative communication are important ways for students to learn mathematics. Practical operation and independent inquiry are also the main ways for students to learn new knowledge in this course, and at the same time pay attention to the guidance of learning methods.

1. Practical operation method, modern educational psychology believes that the development of children's thinking is the transition from concrete image thinking to abstract thinking. They need to learn knowledge and develop wisdom through various activities. Therefore, in the teaching example of 1, each student is designed to draw the shape of the observed puppy, and through hands-on painting, he can personally feel and experience that the shape seen by observing objects from different angles is different, and gradually develop the concept of space.

2. Independent inquiry teaching emphasizes that students are the main body and participate in the process of knowledge formation, so as to always provide students with sufficient learning materials, create sufficient learning space and time, let students explore independently, experience the process of knowledge formation, and cultivate the ability of active inquiry. For example, when teaching symmetrical graphics, students carefully observe, compare and analyze the characteristics of symmetrical graphics in activities such as overlapping, drawing and comparing.

3. Observation methods Example 1 Observation of objects, Example 2 Observation of symmetrical graphics teaching are all good learning methods. For example, when teaching example 1, the observation purpose is clear. The teacher asked the students to observe the toy dog and draw a puppy, and then observe the puppies drawn by other students. After the observation, the teacher organized a discussion to discuss why students draw different shapes for the same puppy. This arrangement not only gives students the opportunity to think independently, but also teaches students the thinking method of observation.

Fourth, talk about teaching procedures.

This lesson is mainly completed by five links.

(A) observation and exploration to cultivate students' concept of space

1. Let the students guess what objects they observe today, and then show the toy dog.

2. Make clear the position, let the students in the group talk to each other and guess where they are sitting on the puppy, and they may see the puppy.

Something.

In this way, the teaching design grasps the characteristics of children's love of playing, actively arouses students' interest in learning, clarifies learning content, reviews old knowledge and prepares for exploring new knowledge.

Step 3 draw a puppy

Let the students sit in their seats and draw the dogs they see. The teacher chooses a picture of a puppy from the front, back and side, and projects the students' works.

4. Questioning understanding

Guide the students to observe and compare the same puppy. Why do they draw different shapes? Organize each group of students to discuss.

Then report the results. Finally, the summary of the introduction: Because the three students observed different positions, they saw different shapes of puppies.

5, comprehensive observation, experience new knowledge.

On this basis, further guide the overall observation. At this time, let the students observe the puppy comprehensively in their favorite way, and guide and summarize that if you want to know an object, you must observe it comprehensively.

6, knowledge application

In this kind of teaching, four students sit in four directions, observe the same object, draw what they see, then organize themselves to question the reasons, and then observe the object in their favorite way. This design conforms to children's cognitive law, cultivates students' spatial imagination, and fully embodies the concept of the new curriculum.

(B) cooperative exploration, understanding of symmetrical graphics

1, guide the classification, and initially perceive the characteristics of symmetric graphics.

First of all, the teacher let the students enter the climax of exploration through the scene of distributing gifts. There are four symmetrical figures and one asymmetrical figure in this gift. The teacher guides the students to observe these figures carefully first, then fold them up, compare them, talk about what they have found, classify them and communicate in groups.

Classification method report. When some students say that combs belong to the same category, tigers, butterflies, leaves and ladybugs belong to the same category, guide all students to observe the operation again and find that the two sides of these figures are indeed the same and equal in size. A preliminary understanding of the characteristics of symmetrical figures.

Then the computer verifies and reveals what a symmetrical figure is on this basis.

2. Know the axis of symmetry

Then the teacher knows the symmetry axis through a series of activities, such as asking the students to find a line friend hidden in a symmetrical figure and telling the name of this line friend.

Symmetry axis of computer demonstration

Finally, the teacher demonstrated the axis of symmetry.

3. (Then) consolidate and deepen, expand and extend.

(This part of the teaching, without the teacher's prompt, directly allows students to take a look and classify them, and on this basis, organizes students to observe, compare and analyze for the second time, learn new knowledge and experience the exploration process on the basis of full practical activities. At the same time, highlight key points and break through difficulties. )

(3) Connecting with the reality of life

1. Courseware shows a group of symmetrical figures in daily life for students to enjoy. Let students feel the beauty of symmetrical figures and stimulate their desire to find symmetrical beauty in life. On this basis, let the students talk about what other objects are symmetrical in shape in life.

(d) Creation, which guides students to create symmetrical graphic competitions under the condition of students' full perception.

(The teaching of the above two sections fully embodies the concept of "Mathematics comes from life and serves life", so that students can feel the beauty of symmetrical graphics, understand the essence of symmetrical graphics, and use symmetrical properties to create beautiful graphics and solve some simple problems. )

Verb (abbreviation of verb) abstract

This class will be over soon. Who can tell us what you have learned from this class? What do you think is the most successful?

The design of the whole class fully embodies that students are the main body and teachers are the organizers, guides and collaborators of students. In the whole teaching process, students always learn knowledge through hands-on practice and independent inquiry. Students love learning, which makes students change from learning to "I want to learn, I will learn", which stimulates students' enthusiasm for learning and cultivates students' inquiry ability and independent learning consciousness.