# Subtract two-digit numbers crossing the tens boundary

I can subtract two-digit numbers crossing the tens boundary.

# Subtract two-digit numbers crossing the tens boundary

I can subtract two-digit numbers crossing the tens boundary.

## Lesson details

### Key learning points

- When subtracting, the known part of the whole can be partitioned further to subtract the tens and the ones separately.
- Partitioning both the whole and the parts when subtracting gives a correct answer when the ones digits bridge 10
- The tens and ones can be subtracted in any order and the remaining part will stay the same.

### Common misconception

Children may spot a pattern and be able to continue it based on noticing numbers simply increasing or decreasing without making the generalisations needed to understand why this happens.

Encourage children to articulate not only the pattern, but also why it has occurred, at first using practical equipment to prove it, then mentally visualising and manipulating the numbers involved.

### Keywords

Partition - To split a whole up into parts; a piece or section of a whole.

Part - A piece or section of a whole.

### 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).

## Video

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## Starter quiz

### 6 Questions

## Exit quiz

### 6 Questions

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