1. Through concrete operation and reasonable reasoning, it is found that how much one number is more than another is calculated by subtraction.

2. We can solve practical problems in life by exploring methods, and cultivate the interest in learning mathematics and the consciousness of applying mathematics in the process of solving problems.

Key points: through intuitive placement, the exploration of new problem-solving methods is led, and the difficulties of finding the difference between two numbers by subtraction are listed: through intuitive placement, the exploration of new problem-solving methods is led, and the teaching process of finding the difference between two numbers by subtraction is listed:

First, create a situation to stimulate interest in tutorial

Dialogue: The teacher is very happy, because today is the teacher's birthday. Do you know how old the teacher is this year? Guess and tell the teacher how old you are this year. Let's compare who is older and who is younger. How old are you (young)? Do you know how to calculate? Lead to the topic of blackboard writing: the practical problem of finding the difference between two numbers

Second, explore independently and solve problems.

1. Show the courseware and ask questions.

Dialogue: Xiaohong and Xiaoming are playing a game of catching flowers. (Show the courseware) What do you see from the picture? What questions can I ask?

Health 1: How many flowers did they catch? Health 2: Who caught more flowers and how much? . . . . . .

2. Guide inquiry and solve problems.

Question: Do you have any way to know how much more red flowers are than blue flowers? Guide students to solve problems by arranging in a row.

If the teacher has a lot of flowers, is it convenient for us to solve problems continuously? Think about it. Is there any other way?

Use the inserted flowers to guide students to think: which flowers are redundant? How did the extra five flowers come from?

Through observation, let the students realize that 8 out of 13, the remaining 6 are more red flowers than blue flowers, and calculate by subtraction.

3, game activities, consolidate the algorithm.

Say: Compare with Zhuo's children to catch flowers and see who catches more. Catch a few more times. For the first time, talk to each other about how to count one type of flowers more than another.

When arranging report activities for children, we should first talk about which flowers are more and how much, and then talk about which flowers are less and how much.

Third, use new knowledge to guide reasoning.

Dialogue: Our game is over. I heard that the students in Class 4 are also holding a competition. Let's go and have a look. Oh, so they are singing.

1, what do you see? What problems can be solved? Communicate with each other at the same table

Show the questions raised by the students: (1) How many more girls are there than boys? (2) How many boys are less than girls? 2. Solve problems independently. Then the group of four will talk about their thoughts when they ask questions. Discussion: There are two problems in the problem. Why use the same formula to solve them?

4. Summary: How many girls are more than boys, and how many boys are less than girls? These two questions can be said to be how different boys and girls are, and they can be calculated with the same formula. Fourth, connect with reality and solve the problem 1, "think and do" problem 1. (1) Students talk about pictures and meanings. (2) Every answer in the book.

(3) communication. How to calculate it? Why? What else can you solve? 2. "Think and act" question 2. The teaching method is the same as above. 3. "Think and act" question 3.

(1) The teacher dictated the story of rabbit and pig skipping rope together. (2) Let students solve problems independently in books.

(3) Thinking in combination with reality. Can a pig jump faster than a rabbit? 4. "Think and act" question 4.

After the students do the questions independently, check the questions with each other in the group. Fifth, summarize the evaluation and apply what you have learned.

Dialogue: What skills have we learned today, children? Can you compare two quantities in real life? Communicate with each other at the same table. What method will you use to solve the problem of comparing two quantities? Do you have any other good ways to tell your classmates?