Analysis of academic situation: children in grade three are generally around ten years old. According to Piaget's classification of children, children at this time are in the specific operation stage (7 ~ 1 1 year old): children have obvious symbolism and logic, can make simple logical deduction, overcome the self-centeredness of thinking, and obtain the concept of conservation and reversible thinking. But at this stage, children's thinking activities are still limited to concrete things and daily experience, lacking abstraction. This unit includes four parts: area and area unit, area calculation of rectangle and square, advancing speed between area units, and solving practical problems with what you have learned. The teaching and learning of these contents are based on students mastering the characteristics of rectangles and squares and calculating the perimeters of rectangles and squares. The length of primary school students' learning area is a leap in the cognitive development of spatial form. Learning the content of this unit well will not only help to develop students' spatial concept and improve their ability to solve simple practical problems, but also lay a foundation for learning the area calculation of other plane graphics in the future.
Teaching content: area example 1.2
Teaching objective: 1. Understand the meaning of area.
Learn to compare areas by observing, overlapping, calculating areas and estimating. Teaching emphasis: let students know the area and understand its meaning with examples.
Teaching difficulties: let students know the area and understand its meaning with examples.
Teaching AIDS: onion video, laptop live ppt.
Teaching process:
First, area PPT represents the meaning of point, line and surface. Animation shows that this line is made up of many points. This plane is made up of countless antennas. Let students intuitively feel the composition of points, lines and planes in art, and then use students' understanding of points, lines and planes in art to stimulate students' interest and discuss the corresponding names of points, lines and planes in art in mathematics teaching. Thereby introducing the topic.
1, intuitive perception on the map. From the map, which is closer to Beijing, Baoding or Tianjin? Comparing the distance is actually comparing (the length of the line). If you compare the area of Beijing and Hebei Province, are you still comparing the length? The area of Beijing on this map is the area of Beijing. What about the area of Hebei Province? Which of these two places is the largest? Find two provinces on the map and compare their areas.
(Design intention: Because of the difference between online teaching and face-to-face teaching. So choose a map to let students intuitively perceive the point, line and surface between their location and the capital. The relationship between. Let students perceive the size and significance of the area. )
2, the size of the surface of the object
(1) The surfaces of objects in surface and line life also have sizes. Look, where is the front of the blackboard? How big is the blackboard? Dog eggs and tofu pudding also found the surface of the blackboard and felt the size of the blackboard surface. Take a look (show the courseware)
Dog egg: Run around the perimeter and say, Here's the blackboard! Too long!
Tofu pudding: Touching the lower right corner of the blackboard, he said: This is the face of the blackboard! How big it is! So who is right? Let's watch a small video (onion video recognition area-edited video) to guide students to answer questions in the video while watching it.
After watching the video, let the students debate who is right or wrong about dog eggs and tofu pudding. (Discriminate that the part surrounded by the perimeter is a surface, and the size of the surface is the area of the blackboard) Explain the correct representation. Summary: area refers to the size of the face, not the length of the line.
(2) Perception in activities ① Touch the plane: Where is the face of the math book? How big is the cover of the math book? Please feel it. Say: The size of the cover of a math book refers to the area of the cover of a math book. Please find the surface of an object around you, touch it and tell everyone. (The size of the face is the area of the face) Can you still find the side of the dictionary? Touch. What did you find? It is said that the size of the dictionary side is the area of the dictionary side; (shows the cylinder) What about the side of the cylinder? What's the difference between this side and those we just touched? Summary: Only by finding the surface can we find the size of the surface. The surface size of an object is the area. It can be the size of one face or the size of multiple faces; It can be flat or curved.
(Design intention: Ask questions and watch the understanding of onion video, so that students can understand its concept, and then solve the problem by themselves, so that students can really apply what they have learned. Then through activity perception, let students understand the meaning of the surface more deeply, let students know that the surface is not only an upward surface, but also a side surface, and let students realize that the surface size of any object is its area. )
3. Feedback exercises
When some objects are printed on paper, they become flat figures. Do all the figures below have areas? Let's talk about it, the teacher concluded: for an unclosed plane figure, there is no definite plane area, so the area cannot be determined. Only closed figures have perimeter and area. ② Let the students draw a square with a side length of 5cm and a side length of 15cm in the exercise book, and then freely choose one of them to start coloring. Look who draws fast and well. Feedback: Why do you all like to draw a 5cm square? Health: Because a 5cm square has the smallest area, it can be drawn quickly.
(Design intention: Let students feel the size of the area further through painting)
Second, further understand the significance of area in comparison.
1. Compare the sizes of graphics: ppt shows the graphics, let the students distinguish them, and then summarize them. The sizes of the two square pictures are quite different. (Observation) ② Two pictures with little difference, and compare the sizes. (Not suitable for observation, leading to overlapping method). ③ Compare the sizes of two pictures with completely different shapes. (Neither of the above methods is applicable). Play the onion video to measure the area. Ask the students to answer the questions while watching.
(Design intent: The onion video is lively and interesting, and the regulations are clear. Think while watching animation, so that students fall in love with thinking and class. So as to better grasp the knowledge of this lesson) The teacher asked: Why do you use different tools for the same drawing? Student's conclusion: The tools used are different in size and shape. According to the students' conclusion, in order to compare the sizes of figures accurately, we should use the same objects to verify them. Show students several expressions. Question: If you want to be more accurate, which method should you choose? Is it hygienic? Through the method that students agree to choose a small square, it is concluded that this method is also called dense shop method, and it can also be defined as a method of several squares. After using onion video to check the students' mastery, practice and expand the classroom test.