Problem-solving Strategies (1) Teaching content: Book IX, pages 63-64, Example 1, Example 2 and Practice Enumeration Problem-solving Teaching Objective: 1, experience the enumeration problem-solving process of simple practical problems, and find all the answers that meet the requirements without missing anything. 2. Learn, communicate and reflect by enumerating problems, experience the application and value of orderly thinking in daily life, and further develop the orderliness and rigor of students' thinking. 3. Further accumulate experience in solving problems, enhance strategic awareness of solving problems, and improve the ability to solve problems. Teaching emphasis and difficulty: be able to analyze information and solve problems by enumerating. Teaching process: 1. Teaching examples 1 For example 1: Uncle Wang forms a rectangular sheepfold with a fence 18 long 1 meter. How many ways can we surround it? Students guess and ask: How many kinds of enclosures are there? What can be done to discuss at the same table? Exchange summary: According to the students' discussion and answers, write on the blackboard: If the length and width of a rectangle are the two results of ordered rice and disordered rice, students think: Given the same four enclosing methods, which one do you prefer? Important: Starting from the width of 1 m, this order will be neither more nor less. Question: Is there a better way to list all the answers? Show the form in time and guide the students to complete the length (meter) and width (meter) of the rectangle of the form. Tip: What should we know before listing the methods? How can I write it to ensure that it will not be repeated or omitted? Comparison and summary: Comparison and calculation Today we will learn an important problem-solving strategy-enumeration method. Just now, the students got the answer through enumeration. Please tell me which enclosure method do you agree with best? Why? Guide students to calculate the area of a rectangle. The length (meter), width (meter) and area (square meter) of a rectangle. What do you find? Summary: In the case of the same circumference, the greater the gap between the length and width of the rectangle, the smaller the area; The smaller the gap between length and width, the larger the area! Second, teaching example 2 Subscribe to three magazines: Science World, Colorful Literature and Mathematical Paradise. At least one, at most three. How many different subscription methods are there? Teacher's question: What strategy are you going to use to solve this problem? Think independently and tell your thoughts to the students in the group! Student list, there may be these kinds of (abbreviated) guide lists: display form, student observation and analysis form. Only order 1 copy? Order two? Subscribe to three scientific worlds, colorful literature and mathematical paradise. Students tick to complete the summary of the table: what should I pay attention to when listing all the answers? It's neither heavy nor leaking. Third, consolidate the exercise 1, complete the reading of "Exercise and Practice" on page 64, and understand the meaning of the question. Thinking: What strategies can be used to solve this problem? Enumeration: 10 and10; 10、8; 10、6; 8、8; 8、6; 6、6。 Question: This is a different situation of Xiaohua's shooting, so how many laps may he get? Solve the problem that10,6 is different from 8 and 8, but the number of rings obtained is equal. Homework: exercise 1 1 question1-3 v. What did you learn in this class? What are your gains and experiences? (2) Teaching content: Example 3 on page 65 of the textbook, "Practice", Practice 1 1, Question 4. Teaching objective: 1. In specific cases, practical problems can be solved by enumeration. Further, I feel that we should follow a certain order when using enumeration, so that there will be no more and no leakage. 2, can experience when using enumeration method does not meet the requirements of the arrangement should be eliminated. Further cultivate the awareness of application, cooperation and communication, and improve the ability to solve problems. Teaching emphasis and difficulty: enumeration, calculation and consideration should meet the requirements. Teaching process: firstly, introduce dialogue to reveal the topic. Students, let's play a game first: How many different ways are there to take out 2 yuan money with 1 and five dimes? Revelation: How to solve this problem? In what order? (deskmate cooperation list completed) 2. Teaching example 3, solving practical problems 1, giving example 3 and reading the questions by name. Q: What do you mean by "every room can't have an empty bed"? Students think independently first, list them in their exercise books, and then communicate in groups. (There are two ways) 2. Comparing the two methods, which order do you think is easier? (It's easier to list from large numbers) 3. Guide exercises, consolidate knowledge 1, and complete "exercises" 2. Complete exercises 1 1 Question 4 (3) Teaching content: exercises 5-9 and thinking questions on pages 66 and 67 of the textbook. Teaching objective: 1. Further understanding of practical problems can be solved by enumerating specific situations. 2. Further feel the orderliness when using enumeration method. 3. Further cultivate the consciousness of using mathematical methods to solve life problems and improve the ability to solve problems. Teaching process: 1. Review what we learned in the first two classes. What did you get? Second, guide the exercise 1, complete the exercise 1 1, question 5. Think independently, complete and modify collectively. Question: What do you think? 2. Complete the exercise 1 1, question 6. Complete independently and modify collectively. Let the students say what they think. Summary: What should we pay attention to when solving problems by enumeration? 3. Complete question 7 of exercise 1 1. Read the question by name and ask: What do you find by looking at the table? Students finish independently and revise collectively. 4. Complete the exercise 1 1, question 8. Read the questions by roll call and ask: What do you mean by "just going east and north"? Instruct students to complete: We can use letters instead of the points where straight lines intersect, and list all the routes in a certain order. 5. Question 9 of completing the route 1 1. Show the questions and ask to read them carefully. Discuss at the same table. The whole class communicates. Third, complete the thinking questions. Show the thinking problem and let the students finish it independently. You can draw a picture in the book.