Create scenarios and use intuition to help students fully understand the meaning of the question.

In order for students to do application problems, students must be familiar with application problems. Only by making students form the habit of carefully examining questions and keeping the plot and quantitative relationship of questions in their minds from beginning to end can they solve problems better.

Use practical examples in life to improve students' interest and let them master the method of solving problems. For example, when teaching three-step calculation application problems, I designed such an application problem: classmates, the teacher wants to ask you for help. Yesterday, the first-grade children rehearsed the program and lined up. When a child said he was hungry, I took out 18 yuan and asked a child to buy instant noodles. He came back and told me that the store only agreed to give 12 set meal at first. I said the wholesale department is much cheaper than yours. The boss said that each package was 0.5 yuan cheaper, and * * * gave me 17 packages. Now please help me calculate whether there is any mistake according to the owner's statement. If you don't give enough, please help the teacher get less after class.

The blackboard says: Instant noodles 18 yuan. At first, the shopkeeper gave 12 packs. Later, each package was cheaper in 0.5 yuan, and * * * gave it to 17 package.

Students speak their own ideas, methods and steps in the process of speaking, and students have mastered the application problems of three-step calculation method in a very short time.

According to the plot of the application problem, demonstrate it directly with real objects, so that students can understand the specific meaning of the problem by observing the change of quantitative relationship. For example, 7 boys and 8 girls are divided into 3 groups, with an average of several people in each group. You can directly invite 7 boys and 8 girls to come up and automatically divide them into 3 groups, with equal numbers in each group. Another example is: there is a bridge with a length of1550m, and a train with a length of100m crosses the bridge at a speed of15m per second. How long does it take for the train to cross the bridge? Guide the students to compare a short pencil to a train and a pencil box to a bridge. Show yourself how the train crosses the bridge. Where does the train cross the bridge? In this way, students will soon understand why the length of the train itself should be included, so as to find a solution to the problem.

Demonstrate by graphic method. Students only need to express the relationship between the part and the whole, and the corresponding relationship between the specific quantity and the ratio, and the task of solving the application problem is half completed. For example, the plot and quantitative relationship of application problems are displayed intuitively with line diagrams, which makes abstract problems concrete and complex relationships clear, and creates conditions for solving problems correctly.

extreme

Training of multiple solutions to one problem

For example, in combination with applied teaching, I showed such a question: "There are 250 students in Hongxing Primary School, and now I want to rent a car for sightseeing. There are two kinds of cars to choose from: 48-seat buses, each with a rental fee of 480 yuan; 20-seat minibus, each 220 yuan. How to rent a car so that every passenger has a seat, which is the most economical? "

To solve this problem, we usually need to design several schemes, and then determine the scheme after comparison. Generally, we should consider the car rental scheme from two aspects: first, rent as many cars as possible with less money for each seat; The second is to minimize empty seats and improve seat utilization.

I let the students design their own plans first, and then communicate with each other. After discussion, the students came up with the following scheme: each bus seat needs 480÷48= 10 (yuan), and each bus seat needs 220÷20= 1 1 (yuan), so that the bus can watch. Because, 250÷48=5 (vehicles) ... 10 (people), you need to rent bus No.5, 1 bus. There are vacancies in this car rental scheme: 20- 10= 10 (units), and the car rental fee is 480×5+220=2620 (yuan).

The above scheme only considers the first aspect, that is, renting more cars with less money per seat, while ignoring the second aspect, even if there are as few empty seats as possible, improving the seat utilization rate. At this time, I inspired the students to make appropriate adjustments on the basis of the above plan, and got the taxi plan: hire 65,438+0 buses less, and add 2 buses, that is, rent 4 buses and 3 buses, so that only empty seats are left: 48× 4+20× 3-250 = 2 (1), and the rental fee is 480× 4. This scheme can not only make every passenger have a seat, but also save the most money.

Variable training

In teaching practice, we can first give the basic conditions, then ask students to change the conditions, questions, structures or narrative forms to make them new topics, and then guide students to compare the previous topics and find out the relationship between them. For example, basic questions: There are 400 girls and 500 boys in a school. What is the ratio of male to female students in this school?

1, change the question:

(1) There are 400 girls and 500 boys in a school. What is the percentage of boys to girls? What is the percentage of girls to boys?

(2) There are 400 girls and 500 boys in a school. How many points are girls less than boys? How many points are boys more than girls?

2. Change the conditions:

(1) There are 400 girls in a school, with 25% more boys than girls. How many students are there in the school?

(2) There are 400 girls in a school, with a ratio of 5∶4. How many students are there in the school?

3. To put it another way: There are 400 girls and 5/9 boys in a school. How many students are there in the school?

Conditional exchange: there are 900 students in one school, and the ratio of male to female is 5: 4. How many boys and girls are there in the school?

Through this kind of training, students can easily understand the relationship between topics and cultivate fluency and flexibility of thinking.