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Using bar models to solve word problems (Part 2)

Maths - Exploring calculation strategies

Mrs Dial

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Exercise book or paper

Pencil

Image credit: Pixabay

In this lesson, you will need:

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Starter quiz

Bar model

Worded problems

Exit quiz

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Keywords

Bar model: a picture of boxes used to assist with problem solving

Cost: how much money you need to spend to buy something

Spend: to give money in exchange for something

4

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5

Bar models

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What is a bar model?

6

74 + 22 =

?

74

22

70 + 20 = 90

4 + 2 = 6

90 + 6 = 96

96

Credit: Mathsbot

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Can you draw a bar model to match these numbers?

5 | 15 | 20

100 | 30 | 70

20

5

15

100

30

70

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Can you draw a bar model and write the number sentence to match this picture?

10

3

7

Credit: Mathsbot

7 + 3 = 10

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9

Can you draw a bar model and a number sentence to match this picture?

10 + 8 + 2 = 20

20

8

2

Credit: Mathsbot

10

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Can you write the equation to match these bar models?

10

85

60

?

60 + = 85

?

70

30

70 + 30 =

Credit: Mathsbot

25

?

100

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Bar model challenge

11

15

10

?

How would you write this as a number sentence?

Can you complete the bar model?

Use inverse operations to write a different number sentence?

Write this as number bonds

What is the total?

Represent this using MAB blocks

Credit: Mathsbot

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Bar model challenge

12

15

10

?

Can you complete the bar model?

Credit: Mathsbot

5

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Bar model challenge

13

15

10

5

How would you write this as a number sentence?

Credit: Mathsbot

10 + 5 = 15

5 + 10 = 15

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Bar model challenge

14

15

10

5

Use inverse operations to write a different number sentence

Credit: Mathsbot

15 - 5 = 10

15 - 10 = 5

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Bar model challenge

15

10

5

Write this as number bonds

Credit: Mathsbot

15

10

5

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Bar model challenge

16

15

10

5

What is the total?

Credit: Mathsbot

The total is 15 because 10 + 5 = 15

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Bar model challenge

17

15

10

5

Represent this using place value knowledge

Credit: Mathsbot

15

10

5

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What is a worded problem?

How do you use math out of school?

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Credit: Pixabay

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Worded problems in life

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Credit: Pixabay

Credit: Mathsbot

Mia has 2 dogs, 1 cat, 1 bird and 2 fish.

How many pets does Mia have altogether?

?

2

1

2+1+1+2 = 6

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Can you draw a bar model to explain this worded problem?

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Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

Credit: Pixabay

Credit: Mathsbot

I have 6 beads to make a bracelet but I need 29.

How many more beads do I need?

29

?

6

6 + ? = 29 or

29 - 6 = 23

You will need 23 more beads to make the bracelet

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Let’s go through that again

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Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

Nikola collects flowers. She has

7 yellow daisies and 8 red daisies.

How many daisies does she have altogether?

?

7

8

Credit: Pixabay

Credit: Mathsbot

7 + 8 =

Double 7 = 14

14 + 1 = 15

Nikola has 15 daisies altogether

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Worded money problems involving change

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Worded problems in life

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Sally went out to dinner on Friday night. She ate a steak and chips that cost her $35, she also had a soft drink that cost $6. How much did her dinner cost?

$35 + $6 =

?

35

6

35 + 5 + 1 = 41

Sally spent $41 on her dinner

Credit: Mathsbot

Credit: Pixabay

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Let’s try this again

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Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

Jackie purchases 2L of milk for $3 and an apple for $1.

What will her change be if she pays $10?

10

?

3

1

$10 - $3 - $1 =

10 - 4 = 6

Jackie will receive $6 change

Credit: Mathsbot

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Your turn to go shopping

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Credit: Pixabay

School canteen menu

Milkshake $3

Cupcake $2

Ice cream $2

Sandwich $4

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Credit: Mathsbot

Credit: Pixabay

Now it is your turn

Paul buys a sandwich and a milkshake from the canteen.

How much money did he spend?

Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

Milkshake $3

Sandwich $4

?

4

3

$4 + $3 =

$7

Paul spent $7 on his lunch at the canteen

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Credit: Mathsbot

Credit: Pixabay

Now it is your turn

Sam buys an ice cream for herself and a

cupcake for her friend from the canteen.

What will her change be if she pays $5?

Cupcake $2

Ice cream $2

Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

5

?

2

$5 - $2 - $2 =

5 - 4 = 1

Sam will receive $1 change

Start by carefully read the question and highlight important words and numbers
Creating a bar model we can get a visual picture to help us solve the problems.

Here we can see that the whole amount Sam has is $5, she has spend $2 on an ice cream and $2 on a cupcake.

We then need to decide if we are going to add or subtract. What we are trying to find is the change Sam will receive so we are wanting to find the difference between the money Sam started with and the amount she will have when she finishes buying snacks from the canteen. This means we need to subtract the amount of money she spent from the $5 she started with
Write the equation. You may find it easier to use your doubles knowledge and add all the cost of the cupcake and the ice cream together and subtract that total from the whole number. In this case Sam an ice cream for $2 and a cupcake for $2. This means her she spent $4 which is what we need to take away from the $5 she began with. So we are going to take 4 from 5
Answer the question. Remember it is really import that you go back and make sure you answer the question.

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Can you draw a bar model to match the items bought from the canteen?

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Milkshake $3

Ice cream $2

Credit: Mathsbot

Credit: Pixabay

5

3

2

$3 + $2 = $5

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29

Credit: Mathsbot

Can you match up the bar models with

the canteen purchase?

Stuart bought a sandwich for $4. He had $10, how much change will he receive?

?

4

10

Sarah has $5 to spend. She has bought a cupcake for $2 and an ice-cream $2, how much change will she receive?

?

4

3

Charlie bought a sandwich for $4 and a milkshake for $3 from the canteen. How much money did Charlie spend?

5

?

2

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Lesson recap

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Lesson review

Worded problems

60 + 30 = 90

90 - 60 = 30

Bar model

Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

60

30

90

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Pause the video to complete your task

Resume once you’re finished

Task headline

Complete the worksheet for “Using bar models to solve word problems (Part 2)”

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Shopping items

Flowers $35

Ball $40

Shoes $80

Books $55

Art supplies $15

Milkshake $3

Cupcake $2

Credit: Pixabay

Apples $10

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Worksheet questions

Using bar models to solve word problems

Solving hint!

Carefully read the question
Highlight important information
Create a bar model
Decide if you are adding or subtracting
Write the equation
Answer the question

4) Amy purchases some flowers, a ball, and a milkshake.

If she had $80, how much money will she have left?

1) Tom buys some books, art supplies and a cupcake. How much money did Tom spend?

2) Sarah buys some apples and a pair of shoes. If she has $100, how much change will she receive?

3) Caleb buys some apples for his mum, a milkshake for his brother and a cupcake for himself.

How much money did Caleb spend?

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Worksheet answers

Using bar models to solve word problems

1) Tom buys some books and art supplies. How much money did Tom spend?

?

55

15

$55 + $15 = $70

Books $55

Art supplies $15

Tom spent $70 altogether

Credit: Mathsbot

Credit: Pixabay

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Worksheet answers

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Credit: Mathsbot

Credit: Pixabay

Worksheet answers

2) Sarah buys some apples and a pair of shoes.

If she has $100, how much change will she receive?

Shoes $80

Apples $10

100

10

80

?

$80 + $10 = $90

$100 - $90 = $10

Sarah will receive $10 change

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Credit: Mathsbot

Credit: Pixabay

Worksheet answers

3) Caleb buys some apples for his mum, a milkshake for his brother, and a cupcake for himself. How much money did Caleb spend?

Apples $10

Milkshake $3

Cupcake $2

?

2

10

3

$10 + $3 + $2 = $15

Caleb spent $15 altogether

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Credit: Mathsbot

Credit: Pixabay

Worksheet answers

4) Amy purchases some flowers, a ball, and a milkshake.

If she had $80, how much money will she have left?

Flowers $35

Ball $40

Milkshake $3

80

?

3

40

35

$40 + $35 + $3 = $78

$80 - $78 = $2

Amy will receive $2 change

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