New
New
Year 3

# Bridge 100 by adding in multiples of 10

I can use number facts to 20 to add multiples of 10 and bridge 100

New
New
Year 3

# Bridge 100 by adding in multiples of 10

I can use number facts to 20 to add multiples of 10 and bridge 100

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## Lesson details

### Key learning points

1. The language of unitising helps us to use number facts to 20 to add multiples of 10 crossing the hundreds.
2. Crossing the tens boundary helps us to cross the 100s boundary if we think in tens.
3. Partitioning an addend helps us to cross the 100 boundary when adding.

### Common misconception

Lack of fluency with number facts to 20 can hinder progress in applying them to multiples of ten.

Ensure that fluency with number facts to 20 is secure or supported so that pupils can apply them.

### Keywords

• Bridging 100 - Bridging 100 means partitioning one addend to make a number bond to 100 then adding the remaining part.

Rehearse number facts to 20 ahead of this lesson and provide support with these if needed. Make use of base ten manipulatives to help pupils to see the structure especially when bridging through 100.
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).

## Starter quiz

### 6 Questions

Q1.
What is the missing part on the bar model?
120
100
Q2.
What is the missing whole on the bar model?
132
130
120
Q3.
Use this bar model. Which addition calculations are correct?
9 tens = 19 tens + 10 tens
Correct answer: 9 tens + 10 tens = 19 tens
Correct answer: 19 tens = 10 tens + 9 tens
9 tens + 19 tens = 10 tens
Q4.
170 = 40 + 100 + . What is the missing part?
Correct Answer: 30, thirty, 3 tens
Q5.
Sophie buys some ribbon that is 170 cm long. She gives 70 cm to her friend. How much does she have left ? cm.
Correct Answer: 100 , 100 cm, one hundred cm, one hundred centimeters
Q6.
Which calculations could represent this bar model?
Correct answer: 140 = 40 + 100
100 - 140 = 40
Correct answer: 100 + 40 = 140
Correct answer: 100 = 140 - 40
100 - 40 = 140

## Exit quiz

### 6 Questions

Q1.
What are the addends in this calculation 90 + 30 = 120 ?
30 and 120
90 and 120
Q2.
If I know 6 + 5 = 11 what is 6 tens + 5 tens?
Correct Answer: 11 tens, eleven tens, 110, one hundred and 1 ten, one hundred and ten
Q3.
Match the tens to the multiples of ten.
Correct Answer:3 tens + 9 tens,30 + 90

30 + 90

Correct Answer:4 tens + 8 tens,40 + 80

40 + 80

Correct Answer:5 tens + 7 tens,50 + 70

50 + 70

Correct Answer:6 tens + 6 tens ,60 + 60

60 + 60

Correct Answer:7 tens + 4 tens ,70 + 40

70 + 40

Q4.
When adding 80 to 60, how can the addend 60 be partitioned to bridge 100?
10 + 50