1, say something.

Children, the campus is our home, and each of us wants to make our home beautiful, right? What do you want to decorate your campus with?

The student said

What a rich imagination you have! I think if we decorate the campus with all kinds of beautiful flowers, it must be very beautiful. Now let's all go to the garden and have a look.

The courseware presents a scene diagram.

Step 2 find information

There are 20 pots of yellow flowers and 30 pots of purple flowers.

ask questions

Question 1: How many pots of yellow flowers and purple flowers are there?

Question 2: How many pots of flowers are left after removing 20 pots of yellow flowers?

Question 3: How many pots of purple flowers are left after the pot of purple flowers is removed?

Second, explore and solve problems independently.

1. How many pots are there in the yellow and purple flowers?

(1) formula calculation.

Why is there addition?

What about 20+30=? What is the number?

& gt(2) Think independently

& gt(3) deskmate communication

& gt(4) Student report

3> method 1: 2+3 = 520+30 = 50

Method 2: 50 can be divided into 20 and 30, so 20+30=50.

Method 3: 50-30=2020+30=50.

Method 4: 2 ten plus 3 ten is 5 and 10 is 50.

(5) Transmission algorithm

Can you understand these algorithms?

(6) Algorithm optimization

2. Solve "How many pots of flowers are left after removing 20 pots of yellow flowers?"

50-20=30

Students talk about algorithms.

Step 3 do this

Show: 30+40; 70-30 & lt；

The teacher led the students to lose their relationship.

Step 4 reveal the topic

Numbers like 20, 30 and 50 are decimal integers. Today, in this lesson, we will learn the addition and subtraction of decimal integers. Blackboard writing: add and subtract integer ten digits

Third, game practice consolidates new knowledge.

1, drive the train.

40+20

60-40

3+2

30+20

40+3 & amp；

40+30

6-4

60-40

95-5

80-80

60+6

66-6

2+3+4

20+30+40

80-50+4

90-60- 10

2. Help the bird find a home.

What if there is another bird without a home?

Infiltrate ideological education in a timely manner. )

Now there is a bird's nest here. What birds can be provided to live in? (Courseware demonstration: 50)

3. buy a ball.

Courseware Demonstration: Volleyball 30 yuan

Football 40 yuan

Basketball, 50 yuan.

Question 1: How much does it cost to buy a football and volleyball?

Question 2: What other questions can you ask?

Question 3: If I give you 100 yuan, how do you buy it?

Fourth, the extension of class summary.

What did you buy today?

Today is to use what you have learned to solve some math problems around you. As long as children carefully observe and think, there are more math problems waiting for you to solve in life!

Chapter II [Teaching Objectives] 1. In the actual situation, further understand the meaning of addition and subtraction, explore and master the calculation method of integer decimal addition and subtraction, understand the diversity of calculation methods, and calculate correctly. 2. Through hands-on, cooperation and communication, I initially experienced the process of asking and solving problems in specific situations, and cultivated my awareness and ability to solve practical problems. 3. Stimulate students' interest in learning and the awareness of active exploration in lively situations.

[Instructional design]

(A) the creation of situations, the introduction of new courses

Teacher: Students, what season is it? Spring is coming, the grass is green, and the small animals in the forest should come out to play. What do you think these little animals are doing? (The courseware shows the situation diagram)

Who can weave this beautiful picture into a story and tell it to everyone? (Students tell stories and pictures)

It turns out that the rabbit is inviting his friends to eat fruit! Rabbit's treat.

Comment on the emotional contact between teachers and students, communicate freely in the form of conversation, use situational teaching correctly and flexibly, make students integrate into the imaginary world, stimulate students' interest in learning and gain positive emotional experience. )

(B) cooperative learning, exploring new knowledge

1. Explore the calculation method of addition

(1) Teacher: Can you ask math questions according to this picture? After thinking, students may ask the following questions:

(1) How many bowls of fruit are there in a * * *? (2) a * * * how many fruits? Focus on solving the problem of how many fruits there are in a * * *.

(2) Teacher: Would you please change the fruit into a stick? Student operation. Help students establish the representation of addition and subtraction. )

(3) Teacher: How to formulate how many fruits are there in a * * *? Answer the blackboard according to the students: 20+30= or 30+20=

(4) Teacher: What is 20+30? what do you think?

Students who can calculate should think about how they worked it out. Other students can use learning tools instead of fruits. )

Organize the whole class to exchange algorithms. The possible methods are as follows:

(1) According to the method of placing sticks, first place 2 bundles of sticks, and then place 3 bundles of sticks to make up 5 bundles, that is, 50 sticks, so 20+30 = 50;

② Because 2+3=5, 20+30 = 50; ③ Because two "10" and three "10" are five "10", 20+30 = 50; (4) By counting 10, 20, 30, 40, 50; ⑤ Dial two beads on the ten digits of the counter, and then dial three beads, which together represent 50, so 20+30=50.

Teacher: Which method do you prefer? Tell your friends your favorite method. (student exchange. )

(Comment on asking questions and trying to solve problems through situations to cultivate students' ability to ask and solve problems. In the calculation, students' thinking angles and methods will be different. Teachers can fully respect these differences and provide opportunities for students to exchange ideas. Through communication, students can choose their own methods independently, which can develop students' thinking ability at different levels and better reflect the diversity of algorithms. )

2. Explore the calculation method of subtraction.

Teacher: Students, please look at what happened. The courseware shows the second picture, and the students tell the meaning of the picture. )

Teacher: According to this picture, what math problems can you ask? Talk about your problems in the group and try to solve your own problems, ok?

(communicate in groups. Teachers patrol and guide to help groups in difficulty. Classroom communication, according to the students' answers on the blackboard: 50- 10=40 or 50-40= 10. )

On the basis that students have explored the calculation method of addition, let students explore the calculation method of subtraction. It is easy for students to change from addition analogy to subtraction, thus cultivating their initial knowledge transfer ability. Solve problems in groups and cultivate students' cooperative consciousness and ability. )

3. Learn the names of each part of the addition and subtraction formula.

Teacher: In the addition and subtraction formula, each number has its own name, just like you. Do you want to know their names? If some students know, let them introduce them. )

Write the following on the blackboard: 20+30=5050- 10=40.

Addition and subtraction

Count reduction

count

The teacher gave another example. Comment in children's language, arouse students' curiosity again, fully respect students' existing knowledge and experience, and let students experience the happiness of success. )

(3) Consolidate practice and expand and extend.

1. Teacher: After eating the fruit, Little Rabbit gave the students some questions! (The courseware is shown below)

(Students answer, talk about the calculation process. )

2. Teacher: The little monkey, the little rabbit and the little hedgehog have a good time. Some small animals are coming. They started the game of finding friends. Can you help them find their friends?

3. Teacher: They finished the game and went to the forest party happily. Many small animals are coming. Look! They are arranging the meeting place! (The courseware shows the situation diagram) What are they talking about?

(Students describe the pictures and answer them. Possible algorithms are: 80-30=50 (sheets); 30+(50)=80 (sheets). Both methods are correct. )

Teacher: After the party, it's time for the animals to go home. Look (courseware presentation).

Teacher: Are these two cars big enough? what do you think? As long as it is a reasonable thinking process, students should be sure. )

(Comments run through practice in the form of stories, which are vivid, interesting and distinct. This design not only conforms to children's characteristics, but also provides enough materials and space for students' thinking, so that each student's thinking ability and problem-solving ability can be developed, especially the open problem of "riding", which cultivates students' ability to solve practical problems flexibly. )

(4) Class summary: Students, are you satisfied with this class? What have you learned?

Article 3 Teaching objectives:

1. Further understand the meaning of addition and subtraction in the actual situation, and correctly grasp the names of each part of addition and subtraction.

2. Be able to add and subtract integer decimal correctly and skillfully, and encourage algorithm diversification.

3. Cultivate students' ability to use mathematical knowledge to solve practical problems.

Learning objectives:

1. Understand the meaning of addition and subtraction, and correctly grasp the names of each part of addition and subtraction.

2. Calculate the addition and subtraction of integer ten plus integer ten correctly and skillfully.

Teaching focus:

Master the calculation method of integer plus integer within 100.

Teaching difficulties:

Cultivate the ability to use what you have learned flexibly to solve practical problems.

Teaching process:

First, review and pave the way

1 The number more than 100 is 99. ()

53 is as big as 35. ()

Numbers before 97 are numbers after 98 and 96. ()

99 is greater than 100. ()

The numbers adjacent to 70 are 7 1 and 72. ()

There are 12 numbers between 6 1 and 73. ()

A number is 1 of several digits, and this number is 5 1. ()

78 consists of 7 1 and 8 10. ()

The median value between 39 and 4 1 is 40. ()

40+5 is smaller than 50+4. ()

Second, create a scene.

Today is bunny's birthday. She wants to invite you to her birthday party. Do you want to attend? (blackboard title: rabbits treat)

Third, explore new knowledge.

1. Look, which good friends did Rabbit invite? The little monkey is a math fan. He found 10 fruits on each plate. Seeing so many fruits, he immediately wanted to ask a math problem. Do you know what questions the little monkey will ask?

(1) Talk to your deskmate. (2) Name communication.

It is not enough to ask questions. Will you solve this problem?

(1) Think it over first, then wave and dial it with your learning tool.

(2) Students in groups exchange ideas and algorithms.

(3) Naming algorithm and formula.

Students report, and the teacher writes on the blackboard: 20+30=50. 30+20=50。

3. Summary: In the addition formula, the numbers before and after "+"are called addends, and the numbers after "=" are called sums.

4. Suddenly, Little Hedgehog has something urgent at home, so let him go home. The hedgehog looked at such delicious fruit and couldn't bear to leave. what should he do ？ He had a brainwave and rolled on the plate. Look, (showing the theme map on the right) he left proudly and made everyone laugh. Children, what math questions will you ask now?

5. Can the above methods be solved by yourself? And tell each part of the subtraction formula.

Group discussion: how to formulate calculation?

6. Ask students to complete the classroom exercises independently.

Fourth, consolidate and improve.

1. Just now, the students all performed very well. The white rabbit decided to take everyone to play a little game. Show your textbook, practice the third question and answer quickly.

2. Three hens can't find their children. Please find out who the mother of each chicken is quickly.

3. Show the orchard map, and let the students ask questions and solve them.

Verb (abbreviation of verb) Teacher's summary:

What did you learn from this course?