New
New
Year 2

Subtract by bridging a multiple of ten

I can bridge ten to subtract single digit numbers from two-digit numbers.

New
New
Year 2

Subtract by bridging a multiple of ten

I can bridge ten to subtract single digit numbers from two-digit numbers.

Lesson details

Key learning points

  1. When we subtract a one-digit from a two-digit number, the equation may be solved more efficiently by 'bridging ten'.
  2. When bridging a multiple of ten, the number that is subtracted is partitioned to reach the previous multiple of ten.
  3. Bridging ten is an efficient strategy because number pairs to ten can be used to calculate more easily.

Common misconception

Children may think the multiple of ten before 43 is 30, or partition the subtrahend incorrectly when bridging, meaning they do not use the most efficient strategy.

Display and use the stem sentences to support articulation of how to find the previous multiple of ten. Use ten frames, number lines and one hundred squares to support with appropriate partitioning of numbers.

Keywords

  • Bridge - A strategy that involves using a multiple of ten as a 'bridge' so numbers can be partitioned to make use of bonds to ten and calculate efficiently.

  • Partition - To split a whole up into parts.

Encourage children to focus on the numbers involved and to predict when solving equations, articulating their thinking and working towards generalisations based on the digits in the numbers involved.
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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6 Questions

Q1.
How would 5 be partitioned to ‘bridge 10’ in this equation? 8 + 5 = 13
1 and 4
Correct answer: 2 and 3
3 and 2
Q2.
How can we solve this equation? 18 + 8 = ?
Partition 8 into 3 and 5
Correct answer: Partition 8 into 2 and 6
Partition 8 into 4 and 4
Q3.
26 + 6 =
Correct Answer: 32
Q4.
What is the missing multiple of 10 on this number line?
An image in a quiz
Correct Answer: 60, sixty
Q5.
‘Bridge 10’ to find the missing sum in this equation. 27 + 6 =
Correct Answer: 33
Q6.
38 + = 43 What is the missing addend?
Correct Answer: 5

6 Questions

Q1.
Look at the ten frames. Which equation does this image represent by showing ‘bridging 10’ to subtract?
An image in a quiz
Correct answer: 15 − 6 = 9
10 − 1 = 9
9 − 6 = 3
Q2.
Look at the number line. How should 8 be partitioned to ‘bridge 10’ when subtracting here?
An image in a quiz
Partition into 4 and 4
Correct answer: Partition into 6 and 2
Partition into 3 and 5
Q3.
How could we solve this equation? 24 − 5 = ___
Correct answer: Partition 5 into 4 and 1
Partition 5 into 2 and 3
Partition 5 into 3 and 2
Q4.
Which number is missing on this number line representation?
An image in a quiz
Correct Answer: 2, two
Q5.
Look at the number line. What is the missing multiple of ten?
An image in a quiz
Correct Answer: 60, sixty
Q6.
64 − 7 =
Correct Answer: 57