First, teaching material analysis:
This lesson is the content of the third information window of Unit 5 in the second volume of Grade Two of Primary School Mathematics in Qingdao Edition. The content of this lesson is to present the scene of forest doctor woodpecker, magpie and oriole catching pests for trees with the help of situation map. The picture provides information about the number of insects caught by three tree doctors. With the help of this information, students are guided to ask questions and solve problems, and the exploration of solving practical problems by using the knowledge of adding and subtracting three digits comprehensively is introduced.
Second, the analysis of learning situation:
Students learned the application problems of "finding the sum of two numbers" and "what is the difference between two numbers", and on this basis, they learned the practical problem of "finding a number that is more (less) than a number".
Third, the teaching objectives:
1. Students can use the knowledge of three-digit addition and subtraction to solve simple practical problems.
2. 1) Go through the process of solving the practical problem "What is the number that is more (less) than a number" and understand the basic methods of solving the problem.
2) In the process of solving problems, experience the connection between mathematics and life, further develop problem-solving strategies, and enhance the awareness of applied mathematics.
3. By exploring mathematical activities to solve problems, we can enhance our self-confidence in learning mathematics well, gain a successful experience and enhance our sense of cooperation.
Third, the importance and difficulty of teaching:
Key points: understand and master the quantitative relationship of application problems with more (less) than one number.
Difficulty: Understand the principle of adding large numbers and subtracting decimals.
Fourth, prepare teaching tools:
Teaching AIDS: multimedia courseware, note.
Learning tools: attention
Verb (abbreviation of verb) teaching process;
(A) stimulate the introduction of interest
Teacher: The teacher brought a riddle. Please see: (showing courseware) There is a bird with high technology. Its sharp mouth loves to cut down trees, and trees and insects eat it, which has made great contributions to greening and afforestation. Tell the teacher what the answer is.
(Woodpecker)
Teacher: the classmate guessed it, it is a woodpecker. Besides woodpeckers, what other birds do you know by name?
Roll call report, collective communication.
Teacher: It seems that people really know about birds. In fact, birds are our good friends. They not only decorate our lives with crisp songs, but also maintain the health of trees with hard work. People call them "forest doctors". Title on the blackboard: Dr. Woods.
【 Design Intention 】 Creating a "forest doctor" scene that students are interested in has stimulated students' enthusiasm for learning and their desire for exploration, laying an emotional foundation for exploring new knowledge in the future.
(2) Explore new knowledge
1. Extract information and ask questions.
Teacher: Please continue to look at the big screen: (student observation)
Teacher: What do you know from the observation just now?
Students report after observation.
The information extracted by the students is as follows: The oriole caught 146 bugs; Magpies catch 38 more than orioles; Woodpeckers catch less than orioles 12 ...
Teacher: According to this mathematical information, what mathematical questions can you ask?
Students ask questions and the teacher writes on the blackboard selectively.
Students may ask the question: How many bugs did the magpie catch? How many bugs did the woodpecker catch? ...
2. Solve "What is a number greater than a number?"
Teacher: The students asked so many questions. Let's solve the first question first, "How many bugs did the magpie catch?"
Ask the magpie how many bugs it caught. You can put it on the table with the note in your hand. Work at the same table, take out the note for you and put it on the table with the teacher. Please take out the white paper first. We use white paper to show the number of orioles catching insects. How many? (Blackboard: 146) If the number of magpies catching insects is represented by a red note, please try. (Students choose one of four red bars with different lengths.)
Two people at the same table choose.
Teacher: Who will tell me which one you chose? (Name it, pick it up when you're finished) Why did you choose this? (Because magpies catch more bugs than orioles) (The teacher took another long one) This one is also longer than white paper. Why not choose? (Health: more than 38, but more, this is much more) Is he right? You are really a clever boy. Let's praise him together.
Teacher: Magpies catch 38 more bugs than orioles. Where should these 38 articles be written? Who can come up and point?
Teacher: (The teacher points to the note on the blackboard) What does the other part mean? What is this question? Where should I write it?
Teacher: In this way, we can clearly see the quantitative relationship between them. Can you calculate the number of magpies catching insects? Solve it yourself in the exercise book.
The students answered, and the teacher named the blackboard.
Teacher: (asking the students on the blackboard) Why do you use addition? What does 146+084 mean? What do you mean by146,38, 184? Do you have any questions for him?
Communicate with the whole class and correct yourself.
3. Solve the practical problem of "how much is a number less than a number"
Teacher: Just now, we learned how to solve problems by analyzing quantitative relations with paper strips. Let's use what we have learned to solve the problem of "how many bugs have woodpeckers caught". When two people work at the same table, you can use a piece of paper or try to draw a line segment to analyze the quantitative relationship.
Teacher: Who wants to come up and show you your solution? what do you think?
Students report, teachers report with students, and courseware demonstrates line charts.
Teacher: As can be seen from the line diagram, catching insects only needs the number of woodpeckers, that is, 146 to get rid of 12. What does the formula rig number mean?
Report by roll call and communicate with the whole class.
【 Design Intention 】 Through hands-on operation and deskmate discussion, students can understand the ideas and algorithms in the process of solving problems, improve their ability to analyze and solve problems, and cultivate the awareness of cooperation and communication. Boldly try to let students transfer the practical problem of finding a number greater than one to the practical problem of finding a number less than one, improve students' comprehensive ability to use knowledge to solve problems, and let students feel the coherence of mathematical knowledge.
New knowledge and new assistants (paper strips) naturally run through students' inquiry, leading students to discover the benefits of putting paper strips and paving the way for learning to draw line segments in the future.