Learning objectives:
1. Let students know the meaning of graphic area by combining concrete examples and painting activities.
2. Let students experience the process of comparing two graphic areas and the diversity of comparison strategies.
3. Cultivate students' hands-on operation ability, comprehensive analysis ability and preliminary space concept in activities.
4. Make students know that there is no only way to solve problems in activities, and develop the ability of cooperation and communication with others.
Learning focus:
Combine specific examples and painting activities to understand the meaning of graphic area.
Learning difficulties:
1, understand the meaning of graphic area.
2, can correctly judge the size of the two graphics areas.
Teaching preparation:
Learning kits, all kinds of objects, courseware, etc.
Teaching process:
First, appreciate the gift and know the meaning of area.
1, know the surface of the object.
(1) Show many "June 1" holiday gifts and ask: This is a holiday gift prepared by the teacher for everyone. Is it beautiful? Show one of the small houses and ask: Who can introduce this gift to everyone?
(2) After the introduction by name, it is explained: In fact, whether it is the top, front or side of the house, we all call it the surface of the house. Are the surfaces of these houses the same? What is the difference?
(3) Demonstration: Many objects in life have faces, such as hands, faces and tables ... Q: What other surfaces can you find? Touch it with your hand and ask: What's the difference between these surfaces?
(4) Description: The surface touched by the students just now is the surface of the object. (blackboard writing: the surface of an object) The size of the surface of an object is the area of this surface. (blackboard writing: the surface size of an object)
(5) (Show several groups of surfaces) Q: Who has the largest surface area? Whose surface area is small?
2, know the closed graphics.
(1) Draw a line:
Students choose an object and draw a surface on white paper.
(2) Comparison:
Show the pictures drawn by students. Q: Is that right? Which side of the object are you describing? Then show the unclosed figure drawn by the students and ask: Is it such a figure? Why not? Finally, we call a graph without gaps a closed graph. (blackboard writing: closed graphics)
(3) say:
Q: What's the difference between these closed figures? Note: a closed figure also has a size, and the size of the closed figure is the area of the closed figure.
3. Understand the meaning of area.
(1) Summary: The size of the curved surface or closed figure of an object is their area. (complete blackboard writing)
(2) Description: In our life, we often encounter mathematical problems related to area. Show pictures of life and experience the important role of "area" in life. )
Second, arrange the cards and compare the area.
1. Show three cards of different sizes and compare their sizes.
Student's game: pick the one with the largest area and lift it! Pick the smallest one and lift it! Q: How do you know who has a large area and who has a small area?
2. Show two graphs with similar sizes and compare their sizes.
Q: Guess which graph has a large area? After the students guess, try to verify the result with the school tools in their schoolbags.
Communicate with the class and show the verification method. (Possible methods are: cutting and spelling, grid counting, etc. )
3. Guide students to appreciate, reflect and evaluate.
Q: Different methods can be used to compare the sizes of two graphs. Which method do you prefer?
Note: There are various methods, so you should choose different methods flexibly according to different situations.
Third, practice the salon and experience the use of the area.
Create a mathematical paradise.
1, complete the second question on page 4 1. The students first estimate which figure has the largest area, and then actually count it. When communicating, ask: whose area is large? How did you know?
2. Complete the third question on page 4 1. After students finish independently, ask: Who will talk about the calculation method of area size? What if the number of squares is less than 1?
3. Complete the 40-page "Draw a Picture". The courseware shows the ship pattern designed by the teacher and asks: What does this pattern look like? What is its area? Then ask the students to draw two different patterns with the same area as required. After exchanging students' works, ask: What do you find by observing these works? Let the students know: different figures may have the same area; The area is the same, but the graphics may be different.
Fourth, the whole class summarizes and expands the learning field.
Q: We met a new friend in this class. What did you get? What else do you want to know about this area?
Summary: In this lesson, students know what an area is and learn to compare the sizes of areas. There are many mysteries related to area in life. You can continue to look for information about the area after class and continue to communicate in the next class.
Teaching reflection:
The concept of "area" is the basis for students to learn geometric shapes. Students should feel and understand the importance and necessity of learning this concept in concrete and vivid situations.
According to the characteristics of teaching content, create various activity situations, enrich students' practical activities, and implement the goal of cultivating and developing spatial concepts. The concept of area is abstract, which will be difficult for students to understand. In order to let students better understand and master the abstract concept of "area", I start from life, let students look for the surface of objects in their lives, touch the surface of objects with their hands, tell them how you feel, and compare the sizes of different surfaces to reveal the surface area of objects through the comparison of surface sizes. Then let the students know the area of the closed figure through the perception of the size of the closed figure. In this way, the layers are deep and interlocking, and students unconsciously understand the meaning of area, giving people a natural feeling.
In the teaching process of this course, I also created a space for students to engage in mathematics learning activities and exchanges. For example, when comparing the sizes of graphic teaching, I ask students to guess first, then think independently and come up with a comparison method. Finally, the group cooperated and explored more comparison methods. Students verify their guesses through practice and operation. By cutting and spelling, counting squares, placing learning tools and other methods, students can fully and actively participate in the learning process, so that different students can achieve different development in mathematics learning and their personalities can be publicized. Let students experience the whole process of knowledge formation, deepen their understanding of the meaning of area, and cultivate the consciousness of analysis, comparison and cooperation.
While imparting knowledge and cultivating students' ability, teachers should also take stimulating and mobilizing students' interest in learning and desire for further study as an important task in classroom teaching. Therefore, in classroom teaching, we should also give full play to the incentive function of classroom judgment. Through encouraging evaluation of students' learning, teachers can enhance students' self-confidence in learning, stimulate their motivation to continue learning, and mobilize their enthusiasm for thinking, especially for underachievers. The sustainability of evaluation should be strengthened. In this class, I also paid attention to the students' evaluation: after the students guessed the size of the rectangular square, my evaluation: what the students just said was our guess, and the bold guess has taken a step towards the correct answer. If you are further away from the correct answer, you should verify your guess. However, the language of sensory evaluation is still not perfect, and efforts will be made in this respect in future classes.