Teaching content:

This lesson is the second part of the second book of grade four, based on the knowledge of quadrangles that students already know. The content of this lesson is to classify quadrangles, so that students can understand the characteristics of trapezoid and further understand parallelogram. Through the study of this lesson, students can master that quadrangles can be divided into parallelogram, trapezoid and other quadrangles according to whether two groups of opposite sides are parallel or not.

Student analysis:

The basic knowledge of geometry, whether it is the characteristics of lines, planes and bodies, or the characteristics and properties of graphics, is abstract and difficult for fourth-grade pupils to master. Therefore, I create a series of activities for students in the classroom, so that students can "learn by doing", "learn by doing", "learn by doing" and "create by understanding". According to the characteristics of students' age, students are given plenty of time by active presentation methods such as folding, contrast, drawing and posing. Through students' multi-level perception and multi-angle thinking, quadrangles are classified and their characteristics are summarized.

Teaching objectives:

1. Knowledge and skills: Through observation, operation and comparison, find the characteristics of quadrilateral edges and classify quadrilaterals.

2. Process and method: Understand and master the characteristics of parallelogram and trapezoid, and cultivate students' observation ability, operation ability and thinking ability in images.

3. Emotion and attitude: Develop students' concept of space and stimulate students' awareness of active participation, self-exploration and innovation.

Teaching emphases and difficulties:

Understand the concepts and characteristics of parallelogram and trapezoid.

teaching process

First of all, an exciting tutorial.

Teacher: Students, there are many figures around us. Today the teacher will take you to visit this magical graphic kingdom. Are you happy? The courseware plays the animation of "Graphic Kingdom". )

Teacher: In the graphic kingdom, there are many graphic members. Do you know them? Courseware plays various graphics: rectangle, square, parallelogram, etc. And guide the students to shout out their names. )

Teacher: In the big family of quadrangles, if you look closely, you will find that they have their own characteristics. In this lesson, we will classify them according to their respective characteristics. (Blackboard Title: Quadrilateral Classification)

[Design intention: Take a trip to "Graphic Kingdom" as a clue of learning activities, so that students have a strong interest and intimacy in learning new mathematical knowledge, and the design can encourage students to actively explore new knowledge. ]

Second, explore the classification

Activity 1: One point.

1.

Teacher: Please observe carefully the eight quadrangles that greeted you just now. What are the characteristics of their profiles?

Show slides, students observe and speak freely. )

classify

Teacher: Can you try to classify them with your clever little brain? After the division, communicate with each other in groups of four and tell me the reasons for your division.

The teacher visited each group and focused on guiding the students to talk about the basis of classification.

3. Feedback

Which group will tell us how different you are first? How to divide it? Students demonstrate the classification method through the video booth, tell the characteristics of each group of quadrangles, and then try to give each group a name. As long as students have sufficient reasons, they should be affirmed and encouraged in time. )

Teacher: Do the other groups have anything to add or disagree with? (Allow the classification methods of each group to be diversified. )

According to the students' speeches, the teacher asked in time: Why do you divide it like this? What's your reason?

4. Induction

Teacher: The wise old man saw that everyone had come up with so many kinds of divisions and wanted to classify quadrangles (courseware demonstration). Why do wise old people divide them like this?

Guide students to find out the characteristics of similar figures and define parallelogram and trapezoid in their own words. After the students made clear the characteristics of the above groups of figures, the teacher emphasized that the figures in group A have two groups of opposite sides and are parallelograms. In group B, only one set of figures is parallel to the opposite side, and they are all trapezoidal.

The graph of group C has no parallel edges and is called a quadrilateral. (This lesson will not be studied for the time being)

Activity Intention: Students fully demonstrate their correct or wrong classification methods and cultivate learning.

Students' practical ability and analytical ability can clearly understand parallelogram and trapezoid through the characteristics of graphics. ]

Activity 2: Fill in and draw a picture.

1. Fill it in.

Complete the "fill in the blanks" of the textbook P32 independently, communicate at the same table and report separately.

Draw a picture

Ask the students to draw the specified figure on the sketch provided by P33. On the basis of painting, guide students to talk about the characteristics of these graphics in their own language and experience the characteristics of these graphics. Choose the students who draw best, show their works by projection and encourage them. )

Activity intention: to further deepen students' understanding of various quadrilateral features in practice. Activity 3: Have a discussion.

Teacher: Students, you did a good job today! But naughty encountered a problem while playing in our graphic kingdom. Can you help him solve it?

Teacher: Does parallelogram include rectangles and squares? (Group discussion, communication) The teacher leads the students to conclude that rectangles and squares are special parallelograms because their two opposite sides are parallel and their four corners are right angles.

Activity intention: Through discussion, let students experience the process of exploring new knowledge, understand that rectangles and squares are special parallelograms, and cultivate students' generalization and induction ability. ]

Third, consolidate new knowledge.

Teacher: Everyone studied hard today, and the teacher was very satisfied with everyone's performance. Let's compete in groups of four to see which group of students can cut the fastest, shall we? Requirements: only cut one knife, complete the requirements of the topic, and pay attention to thinking and discussion before cutting each knife.

How to cut clearly, why to cut like this, and what kind of results may appear after cutting.

Activity Intention: Let students further consolidate the concepts and characteristics of parallelogram and trapezoid in the process of hands-on operation. ]

Four. abstract

Teacher: Today's pleasant trip to the graphic kingdom is coming to an end. What have you learned and what do you want to know?

Encourage students to recall what they have learned and talk about learning methods and the gains of this class.

[Design intention: Through the students' self-summary and combing of knowledge, give full play to the main role of students' learning, and also play a good role in reviewing and summarizing knowledge. ] Teaching reflection

In this class, I teach around four links: stimulating interest, guiding the classroom, classifying and exploring, consolidating new knowledge and summarizing. In classroom teaching, we should not only pay attention to the learning results, but also pay attention to the learning process to guide students.

Take the initiative to explore and discover for yourself. In class, I created a series of activities for students, such as marking, filling in, drawing, discussing and skill competition. Let students learn by doing and do by doing.

Enlightenment, enlightenment, creation. Through the multi-level perception and multi-angle thinking of students' hands, brains and mouths, quadrangles are classified and their characteristics are summarized, so that students' knowledge and ability can develop synchronously.

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