Teaching objectives

(1) helps students to further understand the structure and quantitative relationship of applied problems they have learned and improve their ability to solve simple addition and subtraction applied problems.

(2) Cultivate students' preliminary reasoning ability and reverse thinking ability.

Teaching emphases and difficulties

Key points: Understand the structure of application questions and the quantitative relationship learned, and fill in the conditions correctly.

Difficulties: Know what conditions are needed to answer the questions in the question, and cultivate students' reverse thinking ability.

Teaching process design

Review preparation

1. Choose the appropriate questions and answer them. (slide)

(1) The school bought 15 footballs and 20 more. _ _ _ _ _ _?

How much did you buy for a * *?

② How many are left?

Formula:

15+20 = 35 (piece)

I bought 35 footballs.

(2) Li Jun raised 26 white rabbits and black rabbits, including white rabbits 10, _ _ _ _ _?

(1) How much is left?

② How many black rabbits are there?

Formula:

26- 10 = 16 (only)

Answer: There are 16 black rabbits.

2. Ask questions orally and then answer them.

(1) Xiaohong hits the ball. She shot 15 for the first time and 10 for the second time.

Students may ask the following questions:

(1) twice * * * is how many times?

(2) How many times did you shoot the first time than the second time?

(3) How many times was the second time less than the first time?

(4) How many times did you shoot the second time, as much as the first time?

Formula: ① 15+ 10 = 25 (below)

②, ③, ④ 15- 10 = 5 (below)

Oral answer: (omitted)

(2) The kitten caught 12 fish and ate 8, _ _ _ _ _?

Students may ask the following questions:

(1) How much is left?

(2) How many more?

Formula: 12-8 = 4 (bars)

Oral answer: (omitted)

Teacher: A simple application problem must have two conditions and one question. If there is any omission, you need to add a complete answer.

Learn a new course

1. Teaching Example 2.

Example 2: Li Guang has a copy. He posted eight photos for the first time. How many photos did he send twice?

(1) Read the questions by name and find out the conditions and problems.

(2) questioning.

Teacher: Can this problem be worked out? What is missing?

Student: This question doesn't count. There is a condition missing.

Teacher: Today, we will learn the conditions for filling in the application questions, and then finish the application questions before answering them.

Writing on the blackboard: the conditions for filling in application questions

(3) Analysis

Show three conditions.

Choose a suitable condition, draw a line and work it out.

(1) How many cards are left?

(2) give grandma 3,

③ Post 6 pieces for the second time,

Teacher: What does this question require?

Health: How many photos do you want to post twice?

Teacher: How many photos do I need to post twice? What are these two requirements?

Health: How many photos need to be posted twice? You need to know how many photos you posted the first time and how many photos you posted the second time.

Teacher: What conditions are mentioned in the question, and what conditions are still missing? Now give three conditions and see which condition is missing from the question.

Ask the students to discuss. (state the conditions to be selected)

(4) Formulating calculation after reading the questions.

Ask a student to read the topic completely after selecting the conditions.

Formula: 8+6 = 14 (sheets)

Answer: Post 14 photos twice.

(5) Imitation exercise-"doing"

Let the students read page 75 of the textbook and do it.

Teacher: What does this question require?

Health: How many white horses does this question need?

Teacher: What do you need to know to ask for more white horses than dark ones?

Health: We need to know how many white horses and dark horses there are.

Teacher: What conditions are given in the question and what conditions are still missing?

Health: One condition is that there are 35 white horses, but the missing condition is how many dark horses there are.

Teacher: Give three conditions to the right, judge for yourself which is appropriate, connect it with the left with a line, and then work it out.

Let the students complete the formula independently. Collective correction.

2. Teaching example 3.

Example 3, there are 22 boats by the lake, _ _ _ _ _ _ _, how many are left? Name the missing conditions and solve them.

(1) Read the questions by name and find out the conditions and problems.

(2) analysis.

Teacher: What is missing from this question?

Health: lack of conditions.

Teacher: What if there are no conditions?

Health: there is a condition to be added.

Teacher: What conditions should I add? What should we think? Please discuss it with your deskmate.

Let students know to think from problems. How many requirements are left, and which two conditions should they know? Now that we know the original 22 ships, what conditions do we need to add?

Teacher: The condition must be suitable for the question to be answered, otherwise it cannot be calculated.

The students replied, "rent out x only" or "cross out x only".

(3) answer.

According to the students' supplementary conditions, the teacher will give a positive answer.

(3) Integrated feedback

1. There are 32 pots of white chrysanthemums and yellow chrysanthemums on campus, _ _ _ _ _ _ _, how many pots are there in Huang Juhua?

Choose a suitable condition, draw a line and work it out.

(1) There are 10 cans in Ju-hua Fen.

(2) There are 8 pots of white chrysanthemums,

(3) There are 6 pots of purple chrysanthemums,

Formula: _ _ _ _ _ _

There are _ _ _ _ _ _ _ pots in Huang Juhua.

2. Make oral supplementary conditions before answering.

(1) organized a visit to Uncle Lei Feng's deeds exhibition in the second grade. _ _ _ _ _ _ _ _, there are 20 girls, how many boys?

Formula: _ _ _ _ _ _

A: There are _ _ _ _ _ _ _ boys.

(2) There used to be 30 cars parked in the parking lot, _ _ _ _ _ _ _. How many cars are parked now?

Formula: _ _ _ _ _ _

A: There are _ _ _ _ _ _ _ cars parked now.

3. There are 25 TV sets in the store, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Inspire students to think that there are 25 TV sets. What conditions are missing? It can be "X units have arrived" or "X units have been sold". Ask different questions according to the conditions and answer them in different ways.

Description of classroom teaching design

I learned to ask questions according to the conditions of application questions. In this lesson, I will learn the conditions for filling in application questions, so that I can further understand the structure of application questions and the quantitative relationship I have learned and improve my ability to answer simple application questions.

In order to consolidate the feedback, three levels of exercises are designed. 1 the question is to choose a suitable one from three conditions; The second question is to ask students to fill in the missing conditions of application questions, which is more difficult than selecting conditions and can cultivate students' reverse thinking. In particular, the second question is more flexible. Students fill in "driving X car" or "driving X car again" in different ways, and it is more difficult to fill in another condition and question.

The content taught in this section can also be divided into two classes according to the actual situation of the students in this class. The first lesson, teaching example 2, completes the exercises in Do-Do and 1 ~ 4 in exercises 19; The second class, teaching example 3, completes the exercises in Do-Do and exercises 5 ~ 8 of 19.

Jinshan translation should be enough.