The content I prepared is the first volume of the fifth grade national standard textbook for primary school mathematics, "Looking for the Law". This content is based on the law of the quantitative relationship between two objects arranged at intervals and the law of the collocation or arrangement of several objects in the fourth grade textbook. Moreover, in the study of lower grades, students have experienced the process of finding simple arrangement rules of numbers or graphics many times. Therefore, students have accumulated some experience in exploring laws and initially have the ability to explore simple mathematical laws.
Judging from the students' knowledge base and the analysis of teaching materials, the teaching objectives we strive to achieve are as follows:
1. Let the students explore and discover the arrangement law in simple periodic phenomena according to the specific situation, and determine what object or figure a serial number represents according to the law.
2. Let students actively experience the process of independent exploration, cooperation and communication, and experience the process of drawing, enumerating and calculating different problem-solving strategies and gradually optimizing methods.
3. Let students experience the connection between mathematics and daily life in the process of exploring laws, and get a successful experience.
Among them, the teaching focus is on the exploration process of determining what object or figure a series represents in the periodic problem. In the problem of calculating and determining the period, the mathematical understanding of what object or figure a serial number represents is the teaching difficulty of this lesson.
In order to highlight key points, break through difficulties, achieve the above three-dimensional goals, create situations, help students explore independently, and encourage students to explore independently. Create an atmosphere of cooperative learning and encourage students to cooperate with each other. Share thinking results and optimize problem-solving strategies. Close contact with life, let students feel the application value of mathematics in solving life problems with knowledge, and cultivate positive emotions and attitudes. Multimedia courseware is used to assist teaching, create real life situations, provide various learning materials and solve teaching difficulties.
Follow students' psychological laws of learning mathematics, and proceed from students' existing life experience and knowledge experience. I finished this lesson in the following seven main links:
(1) Create situations and perceive laws.
(2) Independent exploration and communication strategies.
(3) Initial application and optimization strategy.
(4) Improve practice and deepen understanding.
(5) Life is full of images and reappears regularly.
(6) Life problems and challenges to wisdom.
(7) Guide reflection and summarize the whole class.
The first part: creating situations and perceiving laws.
At the beginning of the class, I used the courseware to show the scene diagram of the textbook example 1. Caption: "National Day parks and streets are decorated with lanterns and colorful flags everywhere. It also adds to the festive atmosphere of the festival. This is one of the beautiful scenes. Let the students talk about what they can see from the picture. According to what rules are potted flowers placed? According to what rules are colored lights and flags placed? "
According to the students' answers, refine them, such as: 2 pots of flowers are a group, each group is blue and red, and the situation is exactly the same. Let students have an essential grasp of the circulation problem.
(In this link, create life situations to stimulate students' interest in learning. Guide students to observe, teachers give appropriate guidance, deepen students' understanding, and prepare for the next exploration. )
Part II: Independent inquiry and communication strategies. This link is the focus of this lesson.
Let the students think about this question independently: in the picture, we see 8 pots of flowers. If we put them down like this, what color is the pot counting 15 from the left? Give them enough time.
After most students solve problems, organize students to communicate in groups. At this time, I will pay attention to the situation of each group, understand the different strategies of students and help students with difficulties.
After group communication, organize the whole class to communicate. Students may appear in the following ways:
1, drawing strategy, using different symbols to represent blue flowers and red flowers until 15 potted flowers, that is, blue flowers.
2. The listed strategies, starting from the left, 1, 3,5 ... (that is, the serial number is odd) potted flowers are all blue flowers, and 2,4,6 ... (that is, the serial number is even) potted flowers are all red flowers. So the pot of 15 is a blue flower.
3. Calculation strategy. Every two pots of flowers are regarded as a group, and the formula is: 15÷2=7 (group) ... 1 (pot). 15 pot is blue flower.
Here method 3 is abstract, difficult to understand, and has a wide range of applications, so it should be analyzed emphatically. I asked the students to talk about the meaning of each number in the formula. Through constant questioning, I made the students understand: because every two pots of flowers are a group, the situation of each group of flowers is exactly the same. 15 pots of flowers can be divided into seven groups, and the remaining 1 pot is the first pot in the eighth group, which is as blue as the first pot in each group. The grouping of 15 potted flowers is shown by courseware, which is convenient for students to understand the algorithm.
Finally, let the students compare these three methods and express their thoughts. If students don't realize that method 3 has wider applicability, don't rush to instill it in students.
(In the above links, students explore and solve problems in life situations. Believing in students' potential and giving them enough time and space will help them form strategies to solve problems. Exchange learning with each other, experience the diversity of problem-solving strategies and feel the importance of cooperative learning. Using multimedia courseware to assist teaching and solve difficulties. )
Part III: Preliminary application and optimization strategy.
Show the first question of "try it" first. Let the students try to answer. Show students different methods when evaluating. Focus on understanding the calculation method. Guide the students to talk about the meaning of each part of the formula. Especially 18÷3=6, through the question: What does it mean that there is no remainder? /kloc-what color is the 0/8 light? It is concluded that every three lights are a group, which is exactly six groups, and the 18 light is just the last light of the six groups, so it should be as green as the three light areas of each group.
If the students don't agree with the simple calculation method, they can ask: What color is the March 8th light? Where is the100th light? Let students realize that calculation is really a simple method.
Then, let the students practice the second question of "Try it". When commenting, let the students talk about the meaning of the formula and the result of the judgment.
(In this link, students will gradually realize the simplicity of calculation methods and the optimization of strategies. In this process, I don't impose my views on students, but speak with facts and let students choose and realize their own construction. After several exercises, students can further understand arithmetic and basically master this method. )
Part IV: Improve practice and deepen understanding.
First, let the students finish the "exercises" independently. After practice, let the students talk about the differences in the arrangement of figures in these questions. How is the 32nd number of each group determined?
Next, let the students sit on the same table with their own Weiqi, place them regularly, and tell what color the 30th grain is. When communicating in groups, let several groups show it on the physical projector and talk about how to judge. You can also quote a serial number according to the real thing, so that students can answer it.
(In this link, with the students' in-depth understanding of arithmetic, their skills gradually become proficient. Students can keep the calculation process in mind, judge directly according to the remainder, and gradually improve the requirements. The second question in this link is an open question. Students participate in questioning and thinking while doing activities, which is conducive to mobilizing students' learning enthusiasm. )
The fifth part: Life image, the law of reproduction.
"There are many cyclical phenomena in nature." Multimedia plays sunrise and sunset, seasonal changes, full moon and lack of moon. "Our understanding and discovery of the law is also quietly changing our lives." The media plays pictures such as neon lights, cloth and floor tiles. Let the students talk about such a regular phenomenon in life.
Let students feel that such laws exist in a large number in life and feel the beauty of mathematics, law and order. )
Part VI: Life problems, challenging wisdom.
From the natural transition of the previous link to the discussion of ecliptic phenomenon. Multimedia display pictures of the zodiac, such as exercise 10 and question 1 in the book, briefly introduce relevant knowledge, and then ask students to answer this question. You can also add some questions, such as: "Xiao Ming is a pupil, and both he and his father are cows. How old are he and his father? " Wait for questions.
Provide students with more challenging and interesting questions and highlight the application value of mathematics. )
The seventh part: guiding reflection and summing up the whole class.
Summarize with the students: What have you gained from your study?