1, let students calculate the carry addition of two digits plus two digits within 50.

2. Enable students to use what they have learned to solve problems in life.

3. Cultivate students' cooperative consciousness and the ability to summarize calculation methods through practical operation.

Teaching process:

Talk: Today, we came to the multimedia classroom for the first time. How do you feel? Please look around. Are you satisfied with the learning environment here? I don't know if the teacher behind you is satisfied with your performance. Do you want to hear what they say about us? Let's show you the best side. Let's go to class

First, the introduction of new lesson situations:

In the multimedia classroom, there used to be 38 chairs for teachers to attend classes. In order to let more teachers attend classes, 25 chairs were borrowed. Please help students think about this problem. About 60 teachers come to class. Can you sit down?

1. In addition to estimating that 60 people are not enough seats, we can also use accurate calculation to solve this problem. (Post the content of this question)

I want to know if 60 people can sit. What do I need to ask first? How many chairs are there? )

3. Who can make a formula according to this content? (blackboard writing 38-25)

(blackboard title: two digits plus two digits)

Today, we will learn the carry addition of two digits plus two digits.

4. Think about what method you can use to calculate this problem. Next, please tell your classmates about your good algorithm, or you can put it on the desktop with learning tools. Ask the team representative to communicate with you later.

5. Which student wants to talk about different algorithms on behalf of the group?

(Reporting communication, writing on the blackboard)

(1) pen algorithm

38﹢25﹦63

3 8

﹢2 5

6 3

② Port algorithm.

30﹢20﹦50

8﹢5﹦ 13

50﹢ 13﹦63

(3) Swing method

Ask a classmate to pose in front of the projector with a learning tool.

6. Use your method to calculate. Although the figures are all right, let's see which method is better.

7. The vertical method is simpler and less prone to errors. Vertical calculation is also called pen calculation. So what should we pay attention to when calculating by hand? (student summary)

(1) The same number is aligned; ② Count from the unit; (3) When the number of bits reaches 10, it can be marked with "1".

Second, the new lesson content exercises:

1, (Problems in Life) Math Book 12 Do an exercise. Students do calculations continuously, and then check whether the exercises are right or wrong between deskmates.

2. Games (picking apples)

Excellent students and teachers are invited to play games together. Guess how much is hidden behind the apple? Whoever guesses correctly will get the apple.

① 3 6 ② 2 8 ③ 5 3

﹢ 2 9 + 4 5 + 3 5

5 3 8

④ 1 7

﹢ 3

Please play another game (test your eyesight).

Judge and correct the wrong questions. Whoever finds a problem, raise your hand and point it out first.

① 3 9 ② 5 4 ③ 4 3 ④ 2 8

+ 2 3 + 2 5 + 3 8 ﹢4 2

5 2 8 9 7 1 7

Third, class extension:

Red flag race

Everyone in this class is doing well. Do you want to show your skills? Ok, let's have a red flag competition in groups, and the winning team will plant the banner of victory. Listen to the requirements of the competition:

(1) each group selects 4 players to participate in the competition;

(2) Which group will win the first and most accurate task;

After watching the Olympic Games, the audience should keep quiet so as not to affect the good performance of the athletes, so please be a civilized audience. .