Student analysis
Before the third grade, the students had already known the plane figures such as rectangles and squares, and the three-dimensional figures such as cubes and cuboids, and learned their characteristics, and also learned to calculate the perimeters of rectangles and squares. By the fifth grade, they will also learn to estimate the area of irregular figures. Students also have rich experience in understanding the surface size of objects. Through observation and hands-on operation, we can compare the areas of two graphs. In this activity, students will boldly use learning tools, come up with various strategies to solve problems, and think and choose more scientific and accurate methods.
Teaching objectives
1, combined with the specific situation, through observation, operation and other activities to understand the significance of the area, initially learn to compare the size of the surface of the object and the closed figure area.
2. By comparing the areas of the two figures, students can understand the diversity of problem-solving strategies, cultivate their practical ability and develop the concept of space.
3. Create purposeful activities to let students experience the process of knowledge formation, cultivate students' awareness and ability of active exploration and unity and cooperation, make students realize the close relationship between mathematics and life, and stimulate students' interest in learning.
Teaching preparation
1, prepared by the teacher: multimedia courseware, schoolbags (one square and one rectangle, scissors, glue sticks, small pieces of paper, coins, etc. )
2, students prepare: schoolbags (one square and one rectangle, scissors, glue sticks, small pieces of paper, coins, etc. ).
Learning method guidance
Observation and comparison, hands-on operation, independent inquiry and teamwork.
Teaching focus
Understand the meaning of area and experience the diversity of comparison strategies.
Teaching difficulties
Understand the meaning of area and compare the size of two graphic areas.
Teaching process:
First, create a situation and introduce the game.
1, listen and calculate 10 channels, the collective number. Focus 25× 16
2. Teacher: All the right students raised their hands and asked two students to sing "clapping songs" together to show their encouragement. Okay？ (The whole class moves in unison)
[Comment: Introducing new lessons with clapping songs. The students are in high spirits. ]
Second, the initial perception, cognitive field
1. Reveal the meaning of area.
Teacher: When we clap our hands, the place where our hands touch is the palm of our hand. Who will touch the palm of a teacher's hand? (Students touch the teacher's palm)
Teacher: Where is your palm? Touch your palm. (Students touch their palms)
Teacher: (touching the cover of the math book) This is the cover of the math book. Which side of the teacher's palm is bigger than the cover of the math book?
Student: The cover of the math book is big, but the palm is small.
Teacher: Would you please finish what you just said?
Student: The cover of the math book is bigger than the palm, and the palm is smaller than the cover of the math book.
Teacher: Hold out your little hand and put it on the cover of the math book.
Health 1: The cover of the math book is bigger than my palm.
Health 2: My palm is smaller than the cover of a math book.
Teacher: Which is bigger, the cover of the math book or the surface of the blackboard?
Health: The cover of the math book is smaller than the surface of the blackboard, and the surface of the blackboard is larger than the cover of the math book.
Teacher: (referring to the blackboard surface) Like here, the size of the blackboard surface is the area of the blackboard surface. (blackboard writing: area) Can you tell me the cover area of the math book?
Student: The size of the cover of a math book is the area of the cover of a math book.
Touch and say.
Teacher: There are many objects around us, such as desks, stools, exercise books, pencil boxes and so on. These objects have faces, and the areas of these faces are large and small. Now, please choose two of them to compare. Which area is large and which area is small?
Student 1: The desktop area of the class is larger than the stool area.
Student 2: The area of the cover of the exercise book is smaller than that of the desk.
Third, compare sizes and reveal definitions.
1, observe and compare.
Teacher: We draw the surface of an object on paper. This is a plane figure. Observe these numbers. What are their characteristics and sizes?
(Show courseware, students judge, compare sizes)
2. Make it clear that closed graphics also have sizes. Their size is the area of the graph.
3. Reveal the definition: the size of the surface or closed figure of an object is their area.
4. (Show the courseware) Determine which of the following figures are closed figures to consolidate the concept.
Fourth, operating experiments and research methods.
1. Show two graphs with similar areas and compare their sizes.
Teacher: The areas of these two figures are similar. Can you see their area?
Health: No, but we can use the overlapping method. (Students demonstrate on the stage).
2. Courseware shows squares and rectangles with similar areas, and students judge the size of the area.
Teacher: What if we can't use the overlapping method? (Student group discussion)
Teacher: For the convenience of comparison, the teacher provided you with some materials: 4 small squares, banknotes and coins. You can use these materials to find a way to compare their sizes.
Students begin to operate and use the learning tools in the learning toolkit to come up with various methods to compare the sizes of two figures. Division patrol guidance.
3. Students demonstrate different methods and choose a more accurate method to measure the area.
4, the teacher leads to the method of counting grids.
The practical application of verb (verb's abbreviation) in solving problems.
1, (courseware demonstration) Compare the sizes of two graphic areas by computing the grid. Raise your hand and answer after observing.
2. Show two squares. Students discuss and decide whether the square method can be used. Let the students know that the grid size should be the same when comparing.
Draw a picture on the 40th page of the book.
Clear area, the shape of the figure can be different.
Sixth, expand (small designers)
Complete the graphic stickers in the grid paper in groups.
1. The gift is from a clever old man. 2. Teachers put forward specific requirements for activities.
3. Show some students' works and compare the graphic areas.
Seven. abstract
What did you learn in today's study?
Teaching reflection: "area" is the content of "space and figure" in mathematics curriculum standard. The content of this lesson is to help students initially establish the concept of area. The concept of area is taught independently in the mathematics textbooks published by Beijing Normal University, with the purpose of changing the previous phenomenon of emphasizing area calculation and unit conversion and ignoring the cultivation and development of students' spatial concept. 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. A large number of "comparisons", "guesses" and "swings" provided in the textbooks will become the activity process that students experience in class. 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.
First, mathematics classroom teaching is closely related to life
"Mathematics Curriculum Standard" points out: "Students' mathematics learning content should be realistic, meaningful and challenging, which is conducive to students' active observation, experiment, guess, verification, reasoning and communication." The learning content comes from the reality of students' life. Learning on the basis of students' existing experience can make learning more effective. Because the learning content is close to students' knowledge and experience, it conforms to students' psychological characteristics, and it is easy to form a knowledge structure, which fully embodies the concept of learning life. 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 with life, and let students find the surface of an object in life, feel the size of the surface of the object, compare the size of the surface of the object, and reveal the area of the surface of the object through the comparison of the size of the surface of the object. In this way, the layers are deep and interlocking, and students unconsciously understand the meaning of area, giving people a natural feeling. It embodies the basic idea of "mathematics classroom teaching should provide students with valuable and interesting teaching content closely related to real life" advocated by modern educational thought.
Second, provide enough time and space for students' activities. In the teaching process of this course, I created a space for students to engage in mathematics learning activities and communication. For example, when teaching the comparison of plane graphic sizes, I first ask students to discuss the methods of comparison in groups, and then verify their guesses through practice and operation. Students use the methods of cutting and pasting, spelling, counting squares, stacking coins, etc., so that 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.
Third, evaluation is particularly important. While imparting knowledge and cultivating students' ability, teachers should also take stimulating 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 lesson, I pay attention to the following sustainability evaluation: after the students guessed the size of the rectangular square, my evaluation: what the students just said is our guess, and guess is a prelude to scientific discovery, and we have taken a wonderful step! But if you want to get closer to the correct answer, you should verify your guess.