This course should guide students to understand the meaning of area through observation, practical operation and other activities, and initially learn to compare the size of object surface and plane figure. In learning activities, we should understand the relationship between mathematics and life, exercise mathematical thinking ability, develop the concept of space, and stimulate interest in further learning and exploration.
Let's talk about textbooks first:
1, oral teaching content
I said that the content of class is the meaning of area (P74-77). This elementary school is in the third grade of mathematics, according to the national standard of Jiangsu Education Edition.
2, indicating the position in the textbook.
This lesson is the first lesson of Unit 9, the area of rectangle and square. It is based on students' study of rectangles and squares and their perimeter calculation. Textbooks help students understand the area by observing, comparing and touching familiar surface sizes. The study of area is the first contact for students, which is relatively difficult. Students have learned this part, laying a foundation for studying the area of plane geometric figures such as rectangle, square and circle in the future.
3. According to the requirements of the new curriculum standards, I designed the teaching objectives of this course from three dimensions: knowledge and ability, process and method, emotional attitude and values:
(1) Give an example to understand the meaning of graphic area.
(2) Experience the diversity of comparison strategies by comparing the areas of two graphs.
(3) Experiential mathematics knowledge comes from life, and there is mathematics everywhere in life; Publicize personality in inquiry and develop good study habits.
4. Based on the understanding and analysis of the teaching materials, I have determined the following teaching emphases and difficulties:
Teaching emphasis: Understand the meaning of area through observation.
Teaching difficulty: learn to compare the size of the surface of the object with the size of the plane figure.
Second, teaching methods and learning methods:
In the second grade, students have known the surface of the object, truly perceived what a surface is, and also known the plane graphics such as rectangular square parallelogram. On this basis, students are guided to understand the abstract concept of "area", and area is the basic knowledge necessary for students to further understand plane graphics or object surfaces. The students in Grade Three have certain hands-on operation ability and the ability to transfer old and new knowledge, so they are fully prepared for the study of this class.
1, teaching method:
This lesson mainly uses the comparison method, through the comparison of different object surfaces or plane graphics, students can realize the size of the area. Make students know how to compare the size of the area in comparison, combine teacher guidance with students' independent inquiry, and give full play to students' initiative in learning.
2. study law:
Hands-on operation: compare the area size through students' hands-on operation.
Self-exploration: when comparing the size of the area, carry out group cooperation and exchange and explore various methods to compare the size of the area.
Third, talk about the teaching process:
According to the above ideas, combined with the characteristics of this course, I designed the following five teaching links:
1, preliminary perception, cognitive area
Look-look at the surface of the blackboard, the cover of the textbook, and realize that objects have faces.
Compare-compare the blackboard surface with the cover of a math book, which is bigger and which is smaller, and realize that the surface of each object has a certain size.
Listen-understand the meaning of the sentence "the size of the blackboard surface is the area of the blackboard surface, which is larger than the area of the cover of the math book", and the meaning of the first perception of the area.
Touch-Touch the cover of the math book and the desktop of the class to experience the objective existence of these surfaces and feel the size of their respective areas.
For example-for example, the surface area of objects, compare their sizes.
At the beginning of the new lesson, let the students compare the size of the blackboard surface and the cover of the textbook by using their existing life experience, and then draw the preliminary meaning of the area. Then ask the students to compare the surface size of the desktop and stool, and talk about the surface size of other objects in life. In the "talk" session, let students experience in a wider range: the objects they see have faces, and the size of each face is the area of this face, so that students can form a preliminary concept of the area.
2, the operation experiment, compare the size
(1) Know the area of the plane figure.
(1) Just now, the teacher drew a face of a cube on the blackboard, and a square appeared, which is a plane figure.
② Question: Does this square have an area?
(3) Name a classmate and draw its area with chalk. Some students draw a plane figure in the classroom exercise book, draw its area with a watercolor pen, and then continue to draw a figure smaller than just now.
In the previous example, students already know that the size of the surface of an object is an area. Through this part of learning, they will transition from a concrete surface to a plane figure, knowing that the size of a plane figure is also an area. In this way, their understanding of the meaning of area will be more comprehensive.
⑵ Compare the area of plane graphics.
① Courseware for example 2, to guide students to read questions.
② If students say that they can see the size directly, remind them on the basis of affirmation that it is sometimes unreliable to observe the size directly, and inspire them to explore other comparison methods.
(3) Before you start the operation, put forward some explanations: these small pieces of paper represent squares and rectangles in the topic; You can use transparent paper, small pieces of paper, etc. Provided by the teacher. The teacher appreciates that you can compare with the materials around you. If not, just look at how the students around you compare, and I believe you will be inspired.
④ Communicate and report, and guide students to summarize three common methods: watching method, overlapping method and measuring method.
⑤ Give a counterexample. Wrap two pieces of wool around their sides, and then compare the lengths of these two pieces of wool. Do the students judge this is the area of the ratio? What is the contrast?
Let students go through the process from directly observing and comparing the size of the area to comparing the size by other methods, give full play to students' initiative, cultivate students' ability of independent learning, hands-on operation and cooperation in the process of discussing, communicating and exploring comparative methods at the same table, and enable students to master commonly used comparative methods.
Step 3 Practice and solve problems
(1) Distinguish area from perimeter. Use actions to represent area and perimeter. The teacher will dictate the things in life and let the students judge for themselves what they are related to.
② Complete the second question "Think about it and do it". Mainly through observation to compare.
③ Complete the third question "Think about it and do it". Inspire students to think about the method of comparison, focusing on how to count the squares contained in the trapezoid.
④ Instruct students to complete the fifth question "Think and do". This is an open question, so students should be given enough time to freely choose graphics for area comparison. If the area is similar, let's say it's similar.
Let students experience that the methods of comparison change with the specific situation in different applications, so as to deepen their understanding of several methods of area comparison and realize their application in real life.
4. Summarize the class and reflect on the gains and losses.
Guide students to reflect: What have you gained from today's study? Is there a problem?
5, extracurricular expansion, sublimation of understanding
Game name: guess. Rules of the game: The class is divided into two groups. When the students here look at the pictures, the students there should close their eyes and not peek. The first group looks at four squares, and the second group looks at six squares. Ask the students to judge the size of two figures according to the number of squares without knowing the size of squares.
Through discussion, it is concluded that when comparing the areas of two graphs, the grid size should be the same.
The design of this link makes students understand that when comparing the area size with several sub-methods, the size of the grid must be consistent, otherwise it will be difficult to compare, which not only enlivens the classroom atmosphere, but also has a positive impact on the learning of the area unit in the next class.