Draft lecture on acute angle and obtuse angle 1 First, lecture materials
Through the study of the first volume of Grade Two, students learned how to distinguish an angle from a right angle. Knowing that the size of an angle is related to the opening degree of both sides, they will use a triangle to judge whether an angle is a right angle. On this basis, let students know acute angle and right angle. Judging whether an angle is a right angle, an acute angle or an obtuse angle is compared with the right angle on a triangle, which reflects the consistency of the method and is easier for students to master.
Second, talk about teaching methods and learning methods.
The teaching object of this class is junior two students. They are young and easily distracted. In order to catch their interest and stimulate their curiosity, I adopted a pleasant teaching method, using lively and interesting playground situations to let students learn in the created situation. At the same time, I also adopted the discovery teaching method, so that children can discover and show corners through cooperation and exchange, which not only enlivens students' thinking, stimulates their cognitive interest, but also gives full play to their learning enthusiasm.
In order to better highlight students' dominant position, in the whole teaching process, students are encouraged to actively move their eyes, start their hands, use their brains and talk, guide them to learn new knowledge through their own learning experience, and actively carry out teaching activities in this class.
Through the study of this part of knowledge, students can use more accurate and specific mathematical language to describe the mathematical phenomena in life and carry out mathematical communication. For example, to describe the three corners on the red scarf, you can say that there are "two acute angles and an obtuse angle", and you can only say that there were three corners in the second grade last semester. In addition, mastering the concepts of right angle, acute angle and obtuse angle can lay a foundation for further study of angle measurement.
Thirdly, according to the requirements of the new curriculum and the positioning of teaching materials, I have determined the teaching objectives of this lesson as follows:
Knowledge and skill goal: be able to recognize acute angle and obtuse angle in combination with life situation, and be able to dictate the characteristics of acute angle and obtuse angle.
Process and Method Objective: Through observation, operation, classification, comparison and other mathematics teaching activities, cultivate students' practical ability and cooperative consciousness, and stimulate students' innovative thinking. Develop the concept of space in the process of exploring simple objects and figures.
Emotion, attitude and values: Through practice, students can gain a successful experience and build their self-confidence. Through the creation of life situation, we can feel that there is mathematics everywhere in life and cultivate students' interest in learning mathematics.
Four. Overall design and description
I arranged four teaching links in this class:
The first link: situation introduction and perception angle.
In this link, I first use the playground that students are interested in as a situational map (physical projection: the situational map on page 37 of the book), so that students can observe and find the mathematical knowledge in the map-the corner. The purpose is to arouse students' intimacy, create a positive learning atmosphere and create a good scene for learning new knowledge. Review the old knowledge and the knowledge about angles learned last semester: the composition of angles, the size of angles, and the size of angles are related to the degree of openness, paving the way for learning new knowledge.
The second link: classification and comparison, understanding acute angle and obtuse angle.
In this part, I divide it into two steps:
The first step is to draw angles and classify them to produce acute angles and obtuse angles.
First of all, I pay attention to using students' existing knowledge and experience and the close connection between old and new knowledge to guide students to draw different angles on four small pieces of paper. Then through the cooperation of four people, these angles are classified together, and students are asked to discuss the methods of dividing angles and divide them into several categories. In the process of student classification, there may be such a division: right-angled (blackboard writing), not right-angled (blackboard writing).
When students have such a division, I will guide students to divide the categories that are not right angles into smaller categories: some are larger than right angles, and some are smaller than right angles (blackboard writing). At the same time, let students talk about how to know that some angles are larger than right angles and some angles are smaller than right angles, so that students can judge acute angles and obtuse angles as clearly as right angles: they are all compared with the right angles of triangles (compare any angle on the blackboard with triangles), which provides a basis for the teaching focus of this course "being able to distinguish acute angles from obtuse angles". Then tell the students that their classification method is exactly the same as that of mathematicians, so that students can feel the successful experience and build their self-confidence. Finally, I started with specific materials and rose to the abstract concept in time, that is, let students name the acute angle and obtuse angle respectively according to their own understanding of the characteristics. In this way, starting from the concrete materials, it rises to the abstract concept in time, which embodies the new teaching concept, and the teaching content of this topic: acute angle and obtuse angle is naturally exposed (blackboard writing).
The second step is to establish the relationship between the three angles.
In order to find out the relationship between acute angle, right angle and obtuse angle, I first ask students to put acute angle and right angle first, and then put obtuse angle and right angle with the activity angle (demonstration activity angle), so that students can draw the relationship between the opening sizes of three angles: acute angle.