1, so that students can use equations to solve the application problem of knowing what the score of a number is.

2. Guide students to use simple fractional division equation to find out the equivalence relation and solve some practical problems in daily life.

3. Further cultivate students' ability to explore and solve problems independently and their thinking ability of analysis, reasoning and judgment, and improve their ability to solve applied problems.

Teaching emphases and difficulties:

1. According to the meaning of fractional multiplication, find out the equivalence relation and list the equations correctly.

2. Analyze the characteristics, solving ideas and methods of fractional division application problems.

Teaching process (this article comes from Feifei. Lesson. One piece Garden, excellent educational resource network);

First of all, create situations and create problems.

Teacher: Students, do you know what is the most abundant substance in our body?

Health: water

Teacher: Yes! Water is the most abundant substance in our body, which is very important to our body and the main component of our human tissues. So do you know how much water in your body accounts for your weight?

2. Show the small blackboard: A child weighs 35 kilograms, and the water contained in his body accounts for 4/5 of his weight. How heavy is the water in his body? Ask students to graphically represent known conditions and problems, and then analyze the quantitative relationship. Whose unit should "1" be? Let the students talk about the process of analysis and thinking and why multiplication is used. )

Second, discuss communication and solve problems.

1, give an example of 1 situation diagram, let students talk about the mathematical information given in the diagram and the mathematical problems to be solved, and screen out the application problems: a child's body contains 28 kilograms of water, and water accounts for his weight. How much does this child weigh? The teacher asked the students to think and answer the following questions.

(1) Ask students to show the known conditions and problems in the question with pictures. Guide the students to draw the picture below. )

(2) Q: Compared with the questions in the review, which of the two questions has the same number? What quantities are different? (group discussion) (water accounts for the same amount; The difference is that the review question is that the child's weight is known to be 35 kg, and the example 1 is that the water contained in the child's body is known to be 28 kg. )

(3) What changes have been made to the known conditions and problems of the two questions? The known conditions of the review questions are the weight of children and the weight of water. The known conditions of example 1 are all related to children. The problem is different. The review question is to find the weight of water. For example, 1 is to find the weight of children. )

(4) Which quantity in the example 1 is the unit "1"? Write the equation relationship between quantities. (The child's weight is "1". The equation is weight × = the weight of water in the body. )

(5) How to solve the equation? (Two students go to the blackboard to answer and show)

When correcting collectively, teachers should pay attention to whether the unknown set by students is correct and whether the writing is standardized, and correct the problems in time when they are found.

2.( 1) Teacher: All right, class, now let's solve the second math problem: What's dad's weight?

Solve this problem according to mathematical information?

Student: Xiaoming's weight is 7/ 15 of his father's (the teacher affirmed the student's answer and pointed out that "the water in an adult's body accounts for about 2/3 of his weight" is an unnecessary condition for cultivating students' ability to screen and use information [this article is transferred from Feifei Curriculum Park. Net])。

(2) The teacher asked, "Xiaoming's weight is 7/ 15 of his father's". Whose weight is "1"? How many shares did you get on average? On this basis, let the students complete the following line drawing.

(3) Q: Why did the last question draw only one line segment, but this question drew two? (group discussion)

(4) Let the students write the equivalence relation, list the equations and complete the solution.

Dad's weight × 7/ 15 = Xiaoming's weight.

① equation solution: solution: let dad's weight be χ kg. ② Arithmetic solution: 35 ÷ 7/ 15 = 75 (kg).

7/ 15 χ = 35 (if students use arithmetic, they should be sure)

χ=35÷7/ 15

χ=75

3. Consolidation exercise: P38 "Do one thing" (students first complete the exam independently, and then the whole class analyzes the meaning of the question and comments together)

4. Summary: The quantitative relationship of fractional application problems is abstract, and it is often necessary to use graphics to express the relationship between known conditions and problems, so when solving problems, we should use line charts to analyze the quantitative relationship and find out the solution ideas.

Third, consolidate the application and improve the internalization.

1, exercise 10, question 1-3. (First analyze the quantitative relationship, then determine the unit "1", and finally solve it. The second question pays attention to guiding students to find that 250ml of fresh milk is unnecessary)

2. Exercise 10, question 6 (guide students to find out the unit "1"-the salary of parents and 1500+ 1000, and then calculate according to the quantitative relationship)

Fourth, review and reflect on sublimation.

In this lesson, we learned the application problem of "How many fractions of a number are known to find this number" in the fractional application problem. We know that if the unit "1" in a fractional sentence is unknown, it can be solved by equation or division.