textbook

I'm talking about Unit 2, Grade Four, Primary School, Beijing Normal University? Lines and angles? The main contents of this unit are: understanding of line segments, straight lines and rays, understanding of right angles and rounded corners, measuring and drawing angles with protractor. This part of knowledge is the basis for students to learn the classification of drawing angles in the future. The textbook focuses on strengthening students' operation activities, guiding students to understand the necessity of measuring angles with protractor, understanding the characteristics of protractor as an angle measuring tool, and understanding and summarizing the methods of measuring angles with protractor in independent exploration.

Say students

Students have a preliminary experience of diagonal knowledge and know that the size of the angle is related to the size of both sides. Some students have a preliminary understanding of protractor, but most students have little experience in measuring angles with protractor. Although the students have a small protractor in their hands, they are not familiar with it. Radial lines and different scales will make students unable to find the angle on the protractor, and how to measure the angle with the protractor is even more difficult. Moreover, in practice, it seems unnecessary for students to measure angles. What they have mastered is completely abstract mathematical knowledge, which can rarely be applied to life.

According to the understanding of the textbook and the students' reality, I set the goal of this class:

Knowledge goal: to know the protractor and the measurement unit of angle; Angle can be measured with protractor;

Ability goal: to cultivate and develop students' operational ability and thinking ability in angle measurement activities.

Emotional goal: 1. Encourage students to try boldly and express actively in the activities, so that students can be brave in exploration and innovation.

2. Apply what you have learned, explain the phenomena in life, let students feel the value of mathematics and cultivate their sense of application.

Teaching emphasis: know the protractor and measure the angle with the protractor.

Teaching difficulty: gradually experience and summarize the method of angle measurement in independent exploration.

Oral English teaching methods and learning methods

The main content of this lesson is measuring angle, which is a kind of learning of knowledge and skills. In the past, teachers explained the demonstration, students imitated the operation, and then carried out a lot of exercises to consolidate this skill. Undoubtedly, this method is inefficient for developing students' thinking ability. The new curriculum standard advocates that effective mathematics learning activities can't just rely on imitation and memory. Hands-on practice, independent exploration and cooperative communication are important ways for students to learn mathematics. Moreover, Mr. Tao Xingzhi said: Teacher Wang's duty is not to teach, but to teach and teach students to learn. Learn to do things and teach learning; The method of teaching should be based on the method of learning and the method of learning should be based on the method of doing. ? Therefore, in this class, I try to make myself the organizer, guide and collaborator of students' learning, return the class to students, let students experience the significance and methods of measuring angles in independent exploration and cooperation, form a sense of measurement and develop students' spatial concept.

On the Teaching Process

In this process, I mainly designed a kite-flying competition, how to judge whose kite flies high and stimulate students' interest in inquiry, and then began to learn new knowledge, and then designed several activities suitable for students to actively participate in, that is, finding and measuring angles, so that students can understand the significance of measuring angles, explore and summarize the methods of measuring angles, and gradually master the skills of measuring angles. Finally, in the study of related phenomena in life, we can understand the role of angle in life, cultivate students' application consciousness and establish confidence in learning mathematics well. Let me say it alone.

First, create situations to introduce new lessons.

First, talk to the students. Do you like kites? Let go? Have you ever participated in a competition?

In this way, arouse students' life experience and stimulate their enthusiasm for learning.

The teacher brought pictures of small animals flying kites to the students. Look, how seriously they take them! It's time for the game, which makes the little monkey who just became a referee a little anxious. He only remembers that the rules of the competition are as long as the rope, and he forgets how to know who flies the kite high. What shall we do? Can you help this little monkey?

Guide the students to make it clear in the communication that if you want to know whose kite flies high, you only need to know the angle between the rope and the ground. The bigger the angle, the higher the kite flies. The angle between the rope and the ground is abstracted with multimedia courseware to help students understand the mathematics in life and form the ability of abstract thinking.

This problem situation can stimulate students' interest in inquiry and activate their thinking, so that students can learn the knowledge of this lesson with strong interest.

Second, explore the method of measuring angle independently

1, recognizing the necessity of using protractor.

You really have a way. If you want to know who flies the kite high, you only need to know the angle formed by the kite line and the ground. But how do you know the angle?

This question further activates thinking, and students will actively participate in the discussion and know the method of angle size, thus leading to the content to be learned in this lesson. Angle measurement? . In communication, students have different ways to know the size of the angle, such as measuring with a smaller angle; Measure with a ruler; Overlap the two angles to compare their sizes; Measure with a protractor.

Here, teachers conform to students' thinking and guide students to use their own methods. In the process of using these methods, students will realize that the method of overlapping two angles is not applicable in this case. Although you can know the size of an angle by measuring it at a smaller angle, you can't know exactly how much one angle is bigger than another. These methods have limitations in use. Only measuring the angle with a protractor is the simplest and most effective. When students have the need to learn, they can put more energy into learning activities.

Step 2 know the protractor

Please take out the prepared protractor and observe it carefully. What do you see?

Report on students' free exchange.

Know the center point on the protractor, 0? Scale line, internal and external circle scale, 18 large square, 180 small square, 1? Angle. Knowledgeability is a unit for measuring angles.

This is what students see when they get the protractor. Guiding students to talk about what they see can help them become more familiar with protractors and keep their interest in learning. Here I will guide the students to report freely first, and then demonstrate the principle of angle measurement with protractor and the names of each part with multimedia. Help students form a more complete understanding.

Step 3 find the angle on the protractor

Your eyes are really bright. You have discovered so many secrets of protractor. In fact, there are still many angles hidden on the protractor. Can you try to find them? Please draw the corner you found on the exercise paper.

The students tried to draw angles on the protractor on the paper.

Which corner did you find? Do you know how big this angle is?

Let the students show their horns in front and try to say how big it is.

This activity is actually the process of experiencing the measurement angle. In this process, students realize that the central point of the protractor is the vertex of all angles, and any two rays drawn from this vertex can form an angle, and each angle can know the degree, paving the way for measuring the angle later.

4. Try to measure this angle

You found so many angles on the protractor. Can you try to measure the angle with a protractor?