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Solve the application problem of multiple relationships
The first volume of the second grade mathematics of Beijing Normal University Edition, Happy Animals, solves the application problems of multiple relationships. The learning goal of this lesson is to understand the meaning of "multiple" and further understand the meaning of division in the process of comparing the quantitative relationship of small animals. Use graphic intuition and division formula to express the multiple relationship between two quantities. Cultivate the preliminary observation and analysis ability, develop the consciousness of mathematical application and the ability to solve problems. Let's think about it. What does "time" mean? In the Han Dynasty, Jia Yi's On Crossing the Qin Dynasty "tasted ten times a million divisions, knocking on the customs and hitting the Qin Dynasty". In fact, "time" is a quantifier. Put two bananas in the first row and three bananas in the second row. We say that the number of bananas in the second row is three times that in the first row. That is to say, there are three 2' s in 6, and 6 is three times that of 2. This shows that "double" is the result of comparing two numbers in daily life and production. In the comparison of large and small numbers, we often regard the smaller number as 1 times, and there are several smaller numbers in the larger number, and the larger number is several times the decimal number. By understanding the meaning of "multiple", we can understand that division can not only represent the average score of a quantity, but also represent the quantitative relationship (multiple relationship) between two quantities. So how to solve the application problem of this multiple relationship? Here are my thoughts:

? First, careful reading and examination of questions are the key.

? Mathematical application problem is a key and difficult problem in primary school teaching, especially the application problem of solving multiple relations learned today, which was initially talked about yesterday, and today's consolidation is not satisfactory. In the final analysis, students don't understand the meaning of the problem. "Read a book a hundred times to see its meaning", in fact, this sentence is also useful in our mathematics discipline. Example 1. Rabbit 15, monkey 3. How many times is the rabbit? Read the application questions several times and you will get a general idea in your mind. The key point of this question is how many times are rabbits than little monkeys? Find out how many times the key words are used, and how to reproduce them in your mind with a pen. Then find out the quantifier 3 and 15, and what their relationship is, so as to clarify the thinking of the application problem, find out the equivalence relationship, and calculate and solve it.

? Second, there are tricks to do "multiple" questions.

? I'll do the formula method

? Mathematics is a discipline that seeks laws. Why some students learn math well is because they have learned how to learn math. So what are the methods to solve the multi-application problem?

? Large number ÷ decimal number = multiple

? Decimal × multiple = large number

? Large number/multiple = decimal number

? In this formula, we can regard large numbers as comparison numbers and decimals as standard numbers. This is clear at a glance. Example 2: Bunny bought 1 pen, which cost 2 yuan money. The calf said that I spent four times as much money as the calf. How much did the calf cost? In this example, the standard number is 2 yuan money and the multiple is 4. We can use the standard number × multiple = comparison number, and 4×2=8 (yuan) can solve the problem of how much calf paste. Some students can't tell the standard number from the comparison number. You should read more questions to see whose number is large, whose number is small and who is decimal. This problem can also be solved by decimal × multiple = large number. With this formula, children will not be confused about division or multiplication.

I'll make a list of equal relationships.

When solving application problems, I usually ask students to talk about their quantitative relationship first and solve problems according to the equivalence relationship. For example, my father bought five sweets and my mother bought four sweets. How many sweets did my parents buy? This equivalent relationship is the number of sugar bought by dad+the number of sugar bought by mom = the total. Some people will say that anyone can do this, so how do you list the multiple quantity relationship? Animals in the zoo are going to have a party! Look who's here. Two little monkeys. Mother asked me to count the people, and as a result, the small animals began to play charades. The elephant said, "Our number is nine times that of the little monkey", and the pony said, "The elephant is three times that of us". So how many ponies and elephants are there? First of all, according to the meaning of the question, let's list the number of elephants = 9 times the number of monkeys. We can tell children that 9 times means 9 copies, and the number of elephants is 9 copies of monkeys, so that students can understand it better and directly list the formula 2×9= 18 (only). So is the number of ponies. Three times the number of ponies = the number of elephants. We know that the number of elephants is only 18. How to explain these three times? Three ponies are the number of 18 elephants, which is equivalent to dividing 18 into three parts equally. How much is each part? In this way, children can easily understand. List the formula 18÷3=6 (only). They won't confuse multiplication with division.

Write it yourself and explain it yourself. It's fun.

Our usual thinking is just to give children application problems directly, but we have never thought about what is the most fundamental thing in doing application problems-understanding the meaning of the problems. This study requires us to change the conventional methods for children. I'll give you a formula to make it up. This is the most commonly used method for me to solve application problems. I will ask them to write different application problems, because this will not only enable students to understand the meaning of application problems, but also exercise their language organization ability and cultivate their interest in learning mathematics. This method is more active in class. How to solve the application problem of multiple relationships? When 12÷6=2 appeared, the students began to compile. For example, I have 12 watercolor pens, and my sister has six. How many times do I have? There are 12 puppies in Xiaohua Mall, and the number of puppies in Xiaohua Mall is six times that of puppies. How many puppies are there? With such a simple formula, many different application problems about the multiple relation can be compiled. Over time, their logical thinking ability becomes stronger and they are no longer afraid of applying problems.

Third, children's mental health education in math class

The fundamental reason why many children are tired of playing truant is that they have been criticized and accused by many people in their study life, even satirized and sarcastic, and have serious psychological problems. As the saying goes, "a good word warms three winters, and a bad word hurts the cold in June." "It is better to praise a child for a long time." In this class, most of our children are unfamiliar with the times. Even after two classes, I found that children still don't understand through homework. There is a little girl with average grades and very poor understanding in class, but she learned it in this class. Why? Because I said, "Good performance today. Everything you did was right. Continue to work hard. " This is our baby. A word of encouragement can often produce unexpected effects and even change a person's life. Evaluating students' learning regularly is an important means to promote students' learning, and at the same time, it can promote and maintain students' mental health. Teachers should update the evaluation concept of students' mathematics learning, not only pay attention to the improvement of students' knowledge and skills, but also pay attention to the changes of students' emotional attitudes and values, so that evaluation can run through the whole process of mathematics learning.

Whether teachers or students, what we need is a pair of eyes that are good at discovering. Teachers should discover the bright spots of children, and children should discover the tricks of mathematics. Let's move on and open the door to our mathematics.