New
New
Year 3

# Solve problems using knowledge of addition and subtraction of multiples of 10

I can solve problems by applying different strategies for adding and subtracting multiples of 10

New
New
Year 3

# Solve problems using knowledge of addition and subtraction of multiples of 10

I can solve problems by applying different strategies for adding and subtracting multiples of 10

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## Slide deck

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## Lesson details

### Key learning points

1. Representations help to identify the calculation needed to solve a problem.
2. Different strategies can be applied to solve different problems.
3. Evaluating or discussing strategies helps to find the most efficient one.

### Common misconception

Pupils not understanding what the problem is asking them to find out and identifying the operation.

Model the use of bar models and manipulatives to represent the problem and how to identify the operation and calculations needed.

### Keywords

• Add - Bringing two or more numbers or things together to make a new total.

• Subtract - Taking one number from another.

• Strategy - A way to solve a problem.

• Part - A piece or section of a whole.

• Whole - All of a group or number.

This lesson separates the identification of the structure of the problem, its representation and the calculation from the solving of the problem. Encourage pupils to see this discussion and representation of the problem as a key part of the process.
Teacher tip

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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## Worksheet

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## Starter quiz

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### 6 Questions

Q1.
140 - 60 = 80. Which number is the minuend in this equation?
Correct answer: 140
60
80
Q2.
140 - 60 = 80. 60 in this equation is the .
minuend
Correct answer: subtrahend
difference
Q3.
Which is the best way to partition the subtrahend in this equation? 150 - 70 = 80
Partition 70 into 10 and 60
Partition 70 into 30 and 40
Correct answer: Partition 70 into 50 and 20
Q4.
What number is missing from this calculation? 120 − 70 = 120 − 20 − .
Correct Answer: 50, fifty, 5 tens
Q5.
Which partitioned subtrahend will help you to bridge 100?
Correct Answer:150 - 90,90 = 50 + 40

90 = 50 + 40

Correct Answer:180 - 90,90 = 80 + 10

90 = 80 + 10

Correct Answer:140 - 50,50 = 40 + 10

50 = 40 + 10

Correct Answer:120 - 50,50 = 20 + 30

50 = 20 + 30

Q6.
Match the missing subtrahends.
Correct Answer:150 − _ = 90,60

60

Correct Answer:140 − _ = 90,50

50

Correct Answer:130 − _ = 90,40

40

Correct Answer:120 − _ = 90,30

30

## Exit quiz

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### 6 Questions

Q1.
Match the amounts to the correct words in this bar model.
Correct Answer:90 p,part

part

Correct Answer:140 p,whole

whole

Correct Answer:50 p,part

part

Q2.
Look at the bar model. How is the missing number calculated?
Correct answer: 120 ml - 60 ml
120 ml + 60 ml
60ml + 120 ml
60ml - 120 ml
Q3.
Read the word problem. Jacob has 170 cm of ribbon. Andeep cuts 70 cm from the ribbon. Izzy cuts 50 cm from the ribbon. How is the missing part calculated?
70 cm + 50 cm
Correct answer: 170 cm - 70 cm - 50 cm
170 cm + 70 cm + 50 cm
170 cm - 70cm
170 cm - 50 cm
Q4.
Read the word problem. Andeep needs 150 grams of flour to bake a cake. There is 60 grams in one bag of flour and 80 grams in another bag. How much more flour does Andeep need? grams.
Correct Answer: 10 , 10 grams, 10 g, ten, ten grams
Q5.
Jacob used partition and bridge through 100 as his strategy to solve 150 p - 70 p. Order the steps using his strategy.
1 - Partition 70 p into 50 p and 20 p
2 - 150 p - 50 p = 100 p
3 - 100p - 20 p = 80 p
Q6.
Read the word problem. Izzy collected rain water outside in a jug. In week 1, there was 60ml of rain. In week 2, there was 10ml more than in week 1. How much rain water did Izzy collect? ml.
Correct Answer: 130 ml, 130, one hundred and thirty, one hundred and thirty ml