1. Explore and master the oral calculation method of multiplying two digits by one digit, and go through the communication process of various algorithms to calculate correctly.
2. Have the consciousness and ability to estimate according to the specific situation.
3. Combined with the specific situation, use multiplication knowledge to solve simple practical problems and feel the application of mathematics in real life.
[teaching material analysis]
This lesson is based on the students' mastery of table multiplication, learning the oral calculation of multiplying two digits by one digit. In teaching, teachers should not only pay attention to whether students can correctly multiply two digits by one digit, but also pay attention to students' learning process, whether each student can actively participate in activities to explore oral calculation methods and solve simple practical problems, whether he can put forward his own ideas and whether he is willing to cooperate and communicate with his peers. In teaching, teachers should pay attention to: when evaluating students' calculation speed, don't put forward too high requirements, let students have a process of gradual improvement; When evaluating students' ability to use multiplication knowledge to solve problems, we should combine the actual situation with students' real life. This class combines the teaching materials and the characteristics of students in this class, and makes the following design.
1. Create a situation and ask questions.
In teaching, students are guided to observe the situation map first by using the life situation provided by the textbook, so that students can ask mathematical questions on the basis of understanding the pictures. In order to stimulate students' awareness of asking questions, we use multimedia to show the teaching situation map and guide students to ask questions after observation, such as: What do you see from the map? What math questions will you ask?
2. Explore oral calculation methods.
Because of the differences of students' knowledge background and personality, students often put forward different calculation methods from their own life experience and thinking. In teaching, teachers should encourage students to think independently, organize students to communicate, experience the different characteristics of various algorithms and the diversity of algorithms in communication and comparison, and cultivate students' independence and flexibility in thinking. In the process of exploration, teachers should pay attention to guiding and helping students with learning difficulties.
3. Use knowledge to solve practical problems.
Because the oral calculation of multiplying one digit by two digits is widely used in life, in teaching, we should first start from what students are familiar with, use the situation of the textbook "Buying a Swimming Ring" to guide students to go through the process of asking questions and solving problems, use the knowledge of multiplication to solve some simple practical problems around them, experience the practical application of mathematics in life, and further deepen the understanding of the meaning of multiplication; According to the actual situation of the class, create a situation suitable for students to learn, such as two chairs at each table. In this situation, students can be guided to ask mathematical questions, cultivate their awareness of finding and asking questions, and improve their ability to solve problems and mathematical thinking.
Analysis of the situation of schools and students
Our school is a modern urban primary school with a long history, strong teachers and excellent school-running conditions. Most students in our class come from this city, and parents attach great importance to their children's education in all aspects. In all kinds of activities organized by the school, we always take the concept of "success starts here" and pay attention to cultivating students' innovative spirit and practical ability. Students' interest in learning has improved, and their desire for active learning has also increased. They feel the joy of success here.
[class record]
(A) create a situation, ask questions
Teacher: Today, the teacher took you to Dongxing Supermarket to see what was available. Please look at the screen (showing pictures of teaching situations). What do you see in the picture? What math questions will you ask?
Health 1: How much does it cost to buy 1 a swimming ring for each of the three children?
Student 2: How much does it cost to buy five swimming rings and 1 ball?
S3: How much does it cost to buy three balls?
How many swimming rings and balls can I buy for 4:/kloc-0: 00 yuan?
Teacher: In this class, let's first solve the problem of "how much does it cost to buy three swimming rings". How much does it cost to buy three balls? "Problems, other problems first deposited in the" problem bank ".
(B) explore oral calculation methods
1. Solve the problem: How much does it cost to buy three swimming rings?
Teacher: Can you give me a detailed answer?
Students calculate 12×3 or 3× 12 independently, and then exchange their oral calculation methods in the group before reporting.
Health 1: 12× 3 is the sum of three 12, 12+ 12 = 36 (yuan).
Student II: If each swimming ring 10 yuan, three swimming rings 10× 3 = 30 yuan. 2 yuan is omitted for each circle, with 2× 3 = 6 (yuan) for three circles and 30+6 = 36 (yuan) for one circle.
Health 3: 12× 3 is three 10 plus three 2, 10× 3 = 30, 2× 3 = 6, 30+6 = 36 (yuan).
2. Solve the problem: How much does it cost to buy three balls?
Teacher: Can you work it out?
Students continuously calculate 15×3 or 3× 15. Talk about their oral calculation methods at the same table before reporting.
Health 1: 15× 3 is the sum of three 15, 15+ 15 = 45 (yuan).
Health 2: 15× 3 is three 10 plus three 5, 10× 3 = 30, 5× 3 = 15, 30+ 15 = 45 (yuan).
(3) apply knowledge to solve practical problems
1. Look at the screen (show the situation diagram of Exercise 3).
Teacher: Who can tell me what you see in the picture?
Students answer according to the pictures, solve problems independently, then communicate in groups, and then communicate with the whole class.
2. Solve problems in combination with reality.
Teacher: Who can tell us how many chairs there are on each table in the class?
Health: 2.
Teacher: May I ask questions?
Health: How many chairs are there in a group?
Answer questions continuously, and then exchange reports.
(4) Summary
What did you buy today?
Teaching reflection
1. Creating situational links aims at cultivating students' ability to observe pictures, comprehensively apply knowledge and ask mathematical questions. I thought that students might ask a few simple questions in combination with textbooks, but I didn't expect that in this case, the questions raised by students were beyond their knowledge, so I fully affirmed them, and then told everyone that they could save them in the "question bank" first and explore and solve them at an appropriate time.
2. In the process of exploring oral calculation methods, students are given enough time to communicate and explore different algorithms, which embodies the idea of algorithm diversification and encourages students to express their different opinions, so students at different levels have improved to varying degrees.
3. The link of "applying knowledge to solve practical problems" aims to be close to students' lives, grasp the excitement of students, and start from the reality of students' lives, so that students can realize that mathematics is around.
The disadvantage of this class is that the students' activities are not wide enough. We can further study how to effectively arrange various forms of student activities and mobilize students' learning enthusiasm.
[Case Review]
The idea of algorithm diversification has been well reflected in this case. This case can use the situation provided in the textbook to guide students to ask questions and solve problems. In the process of solving problems, teachers can fully let students explore the oral calculation method of multiplying two digits by one digit, and cultivate the independence and flexibility of students' thinking through independent thinking, group communication, exploring various algorithms and communicating with others. Through the application of knowledge, enhance students' application awareness and improve their ability to solve problems. In teaching, teachers can let students express themselves in their own language without forcing students to practice a unified language.