New
New
Year 3

# Bridge 100 by adding or subtracting a single-digit number

I can bridge 100 by adding or subtracting a single-digit number.

New
New
Year 3

# Bridge 100 by adding or subtracting a single-digit number

I can bridge 100 by adding or subtracting a single-digit number.

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## Lesson details

### Key learning points

1. Knowledge of number facts to 20 can support calculation across the 100 boundary.
2. If 8 plus 7 is equal to 15 then 98 plus 7 is equal to 90 plus 15 which equals 105
3. Knowledge of place value can help when counting forwards across the 100 boundary.

### Common misconception

Pupils may not partition numbers in efficient ways to add and subtract them.

Encourage pupils to add or subtract to make 100 (e.g. when calculating 103-7, subtract 3 to equal 100, then subtract 4 to equal 96).

### Keywords

• Bridging - A strategy which uses addition or subtraction to cross a number boundary.

• Partition - The act of splitting an object or value down into smaller parts.

Pupils will need to have a good grasp of number pairs that total 10 to access the learning in this lesson. Base 10 blocks may be useful for this lesson, although pupils will need to use this flexibly alongside the images provided.
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 addend? 6 + = 10
Q2.
What is the most efficient way to partition 6 to complete the calculation 7 + 6?
4 and 2
5 and 1
Q3.
What is 1 more than 99?
Q4.
105 − = 100
Q5.
What number is shown by the arrow?
105
115
135
Q6.
Match the base ten representations to the numbers.

111

110

101

## Exit quiz

### 6 Questions

Q1.
What is the missing addend? 96 + = 100
Q2.
What's the most efficient way to partition 7 to complete 99 + 7 = 106?
2 and 5
3 and 4
Q3.
What calculation is represented?
99 + 4 = 103
98 + 3 = 101
Correct answer: 98 + 4 = 102
97 + 5 = 102
Q4.
What addend is missing from the number line representation?
Q5.
What is the missing number? 108 − = 99
Q6.
Match the equations to the answers.

96

Correct Answer:102 − 7 = ,96

96

Correct Answer:99 + 6 = ,105

105

Correct Answer:98 + 8 = ,106

106