What I want to discuss with you today is the content on the second and third pages of Unit 1, Book 5 of Primary School Mathematics published by Beijing Normal University-"How many small trees are there". This is the first lesson of the new semester on the basis that students have mastered the multiplication formula skillfully last semester. The textbook uses the specific situation of three bundles of small trees to guide students to further explore a verbal calculation method of multiplying numbers by whole ten, whole hundred and whole thousand in activities.
The content of this unit is oral arithmetic multiplication and division, which mainly lays the foundation for learning written arithmetic multiplication and division in Unit 4 and Unit 6. This unit is divided into two parts: the first part is to learn the oral calculation of integer ten, integer hundred, integer thousand multiplied by one digit, and two digits multiplied by one digit (the product is less than one hundred), which are arranged in two situational activities: "How many small trees are there" and "How much money is needed"; The second part is to learn to divide whole ten, whole hundred, whole thousand by one digit, and two digits by one digit. The study of these contents is arranged in two situational activities: "visiting the Science and Technology Museum" and "planting trees". The content of this unit is based on the students' mastery of multiplication and division in the table, which is the basis of learning multiplication and division of multiple digits. The class schedule is 8-9 class hours.
Second, the analysis of learning situation
Students in grade three are active in thinking and enthusiastic in answering questions, plus Protestantism.
The materials are illustrated and illustrated, so students can operate by themselves and communicate with each other. Students love and dare to do it.
It is said that students are always in a state of being willing to explore and actively learn in the process of learning mathematics.
Students can choose their favorite calculation method.
Third, the teaching objectives
1. Students can explore and master the oral arithmetic methods of multiplying integer ten, integer hundred and integer thousand by one digit in specific situations, and experience the diversity of algorithms.
2. Cultivate students' awareness and ability to ask and solve problems in the process of discussing and solving practical problems.
3. Cultivate students' oral expression ability, generalization ability, oral expression ability and knowledge transfer ability.
4. Cultivate students' good habit of listening carefully.
Fourthly, the importance and difficulty of teaching.
The key point is to explore and master the oral calculation method of multiplying integer ten, integer hundred and integer thousand by one digit, realize the diversity of algorithms and calculate correctly.
The difficulty is: how to find the law and understand the oral calculation when the multiplier is integer ten, integer hundred and integer thousand times one digit.
Teaching design of verb (abbreviation of verb)
(A) create a situation, stimulate interest, clear goals
1, creating a wonderful environment. Interest is the best teacher and an inexhaustible motive force for learning. At the beginning, we should introduce it like this: Students, do you know the benefits of afforestation to mankind? Every year in March 12 Arbor Day, garden workers should prepare many saplings to plant trees! So today, let's take a look. What math knowledge is there in the small tree waiting to be planted? At this time, multimedia is used to show the teaching situation map to guide students to observe.
(Design intention: Create a familiar life situation of tree planting for students, closely connect mathematics with real life, and at the same time infiltrate environmental education into students. )
2. Clear goals. In the past, the teaching objectives of each class were put forward by the students themselves, so this class also adopted this method. Students will set the following goals: (1) Look at the pictures to find out the mathematical information, and (2) ask mathematical questions. (3) Solve mathematical problems (4) Discover mathematical laws. Students carry out group cooperative learning with such learning goals.
After observing the picture, the students will find that there are 3 bundles of small trees, and each bundle has 20 such mathematical information. Students will also ask, "A * *, how many small trees are there?" Such a mathematical problem.
(Design intention: to cultivate students' awareness and ability to ask and solve problems in specific situations. The design of this link is mainly based on the fact that students are in the third grade and have the ability to interpret the implied meaning in the situation. Teachers let students observe themselves and learn how to find effective information from situations, which is also a strategy to cultivate students to learn to learn. )
(B) guide to explore and solve problems
1, students list the formulas independently and answer them in groups.
Students list the formula of 20×3 and try to calculate it. Ask the students to talk about the meaning of their listed formulas in the group, and then talk about the calculation method.
(Design intention: The teacher fully allows students to explore the oral calculation method of multiplying an integer by a number, and cultivate the independence and flexibility of students' thinking through independent thinking, group discussion, exploration of various algorithms and communication with people.
. ) [2, the whole class exchanges
The representative of the group spoke, and it was concluded that 20 in 20×3=60 means that there are 20 trees in each bundle, 3 means 3 bundles, and 60 means that a * * * has 60 trees. The students got the calculation method:
① 20×3 is the sum of three twenties: 20+20+20=60.
② Because 2×3=6 and 20×3=60.
③ 20 can be regarded as 10×2, so 20×3 can become 10×6=60.
……
As long as students' calculation methods are correct, teachers should encourage and praise them, and ask students to choose their favorite methods for calculation.
(Design intention: In order to reflect the diversity of students' algorithms, classroom communication is more convenient for students to choose their favorite calculation methods. )
(C) consolidate the practical application of new knowledge
Multimedia presentation: How many trees are there in a bundle of four? How about five bundles?
Please try to solve it first. Then communicate in groups and report to the class.
Design intention: through the application of knowledge, enhance students' application awareness and improve students' ability to solve problems. )
(4) Summarize and extend the exploration.
1, expanding exercise 3×2 5×4 6×7
30×2 50×4 6×70
300×2 500×4 6×700
Students calculate independently and feed back the calculation results.
Teacher: What are the rules of the above formula? In your own words, what did you find?
Guide students to sum up. If one multiplier remains unchanged, the other multiplier will be enlarged by 10, 100, 1000, and the product will be enlarged by 10, 1000.
(Design intention: Let students express themselves in their own language, and cultivate students' language expression ability and ability to discover mathematical laws. )
2, math games:
The teacher prepares cards in advance and plays games at the same table.
Rules of the game: one student takes a number, the other student takes an integer of ten or one hundred, and then both students calculate the multiplication result of these two numbers to see who can calculate quickly and accurately.
(Design intention: The game link is created to stimulate students' interest in learning mathematics, mobilize students' various senses, and cultivate students' flexibility and independence of thinking. )
3. What did you learn in this class? Let the students talk about their own gains.
VI. Summary:
In short, in this class, I use the situation provided in the textbook to guide students to ask questions and solve problems. In the process of solving problems, I fully let go and let students explore the oral calculation method of multiplying ten by one. Students can cultivate their independence and flexibility of thinking through independent thinking, group discussion, exploring various algorithms and communicating with others. In teaching, I ask students to express themselves in their own language instead of forcing them to practice in a unified language, so that students can learn in a free, democratic and harmonious atmosphere.
Because this class is the first class in the new semester, I pay more attention to the training of calculation methods in the design of exercises. I think the next math class should be properly strengthened in applying knowledge and solving problems, so that students can learn and use math better.