Solve word problems (continued)

### 1.1. Knowledge to remember

– Identify word problems with given numbers (known things) and numbers to find (unknown things);

– Understand math for what? What to ask ? And the solution to the problem has a subtraction.

– Know how to solve problems including: Answers, calculations and answers.

### 1.2. Types of Maths on Solving word problems (continued)

**Form 1: Complete the summary and missing math problems.**

– Based on the problem, determine the initial quantity and the amount to be added or subtracted, the requirements of the problem.

– Use the appropriate calculation to fill in the dots.

**Form 2: Solve word problems.**

– Read and analyze math problems, identify known values, problem questions, summarize problems.

– Find a solution to the problem: Based on the keywords in the problem such as “increase”, “decrease”, “more”, “less than”, “all”, “remaining”….to determine determine the appropriate math.

Usually, if the problem requires finding “remaining”, I usually use subtraction.

– Present the solution of the problem: solution, calculation, answer.

– Check the solution, the result just found.

### 1.3. Solve textbook exercises pages 148, 149

**Lesson 1 page 148**

There are 8 birds perched on the tree, then 2 birds fly away. How many birds are left on the tree?

**Summary:**

Yes: …..the bird

Fly away:…the bird

The rest:….the bird?

**Solution**

The remaining birds are:

…………=….(child)

Answer: …. the bird.

**Solution method**

– Read the problem and then fill in the given data in the summary and understand the requirements of the problem.

– To find the solution, we subtract the original number of birds from the number of birds that flew away.

**Solution guide**

**Summary:**

Yes: 8 birds

Fly away: 2 birds

Left:….the bird?

**Solution:**

The remaining birds are:

8 – 2 = 6 (bird)

Answer: 6 birds.

**Lesson 2 page 149**

An has 8 balls, An drops 3 balls. Ask An how many balls are left?

**Summary:**

Yes:……balls

Dropped:….ball

Left:….ball?

**Solution:**

…………………………… ……..

…………………………… ………

Answer:………………………..

**Solution method**

– Read the problem and then fill in the given data in the summary and understand the requirements of the problem.

– To find the solution, we subtract the number of balls we had at the beginning minus the number of balls dropped.

**Solution guide**

**Summary:**

Yes: 8 balls

Dropped: 3 balls

Left:….ball?

*Solution:*

An remaining number of balls is:

8 – 3 = 5 (ball)

Answer: 5 balls.

**Lesson 3 page 149**

The ducks have 8 ducks, 5 of them are in the pond. How many ducks are there on the shore?

**Summary:**

Ducks have: …..con

In the pond: ……con

On the shore: …… child?

**Solution**

……………………………

……………………………

……………………………

**Solution method**

– Read the problem and then fill in the given data in the summary and understand the requirements of the problem.

– To find the solution, we subtract the number of ducks in the pond from the number of ducks in the whole herd.

**Solution guide**

**Summary:**

Ducks have: 8 ducks

In the pond: 5 fish

On the shore: …… child?

**Solution**

The number of ducks on the shore is:

8 – 5 = 3 (duck)

Answer: 3 ducks.

### 1.4. Solving Textbook Exercises page 150

**Lesson 1 page 150**

The store has 15 dolls, sold 2 dolls. How many dolls are left in the store?

**Summary**

Yes: …dolls

Sold: …dolls

Left: … doll?

**Solution method**

– Read the topic, fill in the given numbers in the summary and understand the requirements of the lesson.

– To find the solution, we subtract the original number of dolls from the number of sold dolls.

__Solution guide__

**Summary**

Yes: 15 dolls

Sold: 2 dolls

Left: … doll?

**Solution:**

The number of dolls left in the shop is:

15 – 2 = 13 (doll)

Answer: 13 dolls.

**Lesson 2 page 150**

There are 12 planes on the airport, then 2 planes fly away. How many planes are left at the airport?

**Summary:**

Yes: … airplane

Fly away: … plane

The rest: … the plane?

__Solution method__

– Read the topic, fill in the given numbers in the summary and understand the requirements of the lesson.

– To find the solution, we subtract the number of planes from the original number of planes

__Solution guide__

**Summary:**

Yes: 12 planes

Fly away: 2 planes

The rest: … the plane?

**Solution**

The remaining number of planes on the airport is

12 – 2 = 10 (airplane)

Answer: 10 planes.

**Lesson 3 page 150**

Fill in the blanks with the correct number:

__Solution method__

Perform the calculation from left to right and then fill in the blank with the appropriate number.

__Solution guide__

**Lesson 4 page 150**

Solve the problem according to the following summary:

Yes: 8 triangles

Coloring: 4 triangles

Do not color: … triangle?

__Solution method__

– Read and understand the information given in the summary and requirements of the problem.

– To find the solution, we subtract the number of triangles we had at the beginning minus the number of colored triangles.

**Solution guide**

The number of uncolored triangles is:

8 – 4 = 4 (triangle)

Answer: 4 triangles.

### 1.5. Textbook exercise solution page 151

**Lesson 1 page 151**

Lan folds 14 boats, Lan gives you 4 boats. How many boats do Lan have left?

**Summary**

Yes:…the boat

For you:…..the boat

Left:…….the boat?

**Solution method**

– Read and understand the problem, write the given numbers in the summary and understand the requirements of the problem.

– To find the solution, we subtract the number of boats that Lan can fold.

__Solution guide__

**Summary**

Yes: 14 boats

For you: 4 boats

Left: …….the boat?

**The answer**

Lan and the number of boats are:

14 – 4 = 10 (the boat)

Answer: 10 boats.

**Lesson 2 page 151**

My family has 9 friends, including 5 girls. Ask how many male friends do you have?

__Solution method__

**Summary**

Yes: 9 friends

Female: 5 friends

Nam: … you?

**The answer**

To find the number of male friends, subtract the number of known female friends from the number of friends in the whole group.

__Solution guide__

The number of male friends in my family is:

9 – 5 = 4 (male friends)

Answer: 4 boys.

**Lesson 3 page 151**

A rope 13cm long, 2cm cut. How many centimeters long is the remaining rope?

__Solution method__

**Summary**

Length: 13cm

Cut away: 2cm

Left: … cm?

**The answer**

To find the solution, we subtract the length of the original string from the length of the cut.

__Solution guide__

The remaining string is centimeters long:

13 – 2 = 11 (cm)

Answer: 11cm.

**Lesson 4 page 151**

Solve the problem according to the following summary:

Yes: 15 circles

Coloring: 4 circles

No coloring: ….circle?

__Solution method__

– Read the given information and requirements of the problem in the summary.

– To find the solution we subtract the number of original circles from the number of colored circles.

**Solution guide**

The number of uncolored circles is

15 – 4 = 11 (circle)

Answer: 11 circles.

### 1.6. Solving Textbook Exercises page 152

**Lesson 1 page 152**

Look at the picture, write in the dot to have a problem, then solve that problem:

*a) Math problem*

There are … cars in the station

there are more …. cars to the wharf.

Ask………………………..?

*b) Math problem*

At first there were 6 birds on the branch

yes….the bird flew away.

Ask……………………. ?

__Solution method__

– Look at the picture and then fill in the numbers and questions in the topic.

– Read the problem again, use reasonable math to solve the problem.

**Solution guide**

**a) Math problem**

There are 5 cars in the station

There are 2 more cars to the station.

How many cars are there in all at the station?

**Solution**

There are all cars in the station are:

5 + 2 = 7 (car)

Answer: 7 cars.

*b) Math problem*

At first there were 6 birds on the branch

Two birds flew away.

How many birds are left on the branch?

**Solution**

On the remaining branch the number of birds is:

6 – 2 = 4 (bird)

Answer: 4 birds.

**Lesson 2 page 152**

Look at the picture, summarize the problem, and then solve it:

__Solution method__

– Based on the picture, write an appropriate problem summary; Pay close attention to the rabbits coming or going out.

Use the appropriate math to solve the problem.

**Solution guide**

*Summary*

Yes: 8 rabbits

Out: 3 rabbits

Left: … rabbit?

*The answer*

The number of rabbits left is

8 – 3 = 5 (rabbit)

Answer: 5 rabbits.

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