# Use knowledge of subtraction facts within 10 to subtract within 20

I can use knowledge of subtraction facts within 10 to subtract within 20

# Use knowledge of subtraction facts within 10 to subtract within 20

I can use knowledge of subtraction facts within 10 to subtract within 20

## Slide deck

## Lesson details

### Key learning points

- Subtraction facts within ten can be applied to subtraction within 20, e.g. if 5 - 2 = 3 then 15 - 2 = 13
- A number line can be used to show the link between subtraction of one-digit numbers and teen numbers.

### Common misconception

Children may rely on counting strategies instead of using known facts to subtract from larger numbers.

Make comparisons between subtraction within 10 and within 20, looking for patterns. Make sure children notice that the ones digit stays the same when we subtract numbers with the same ones digits such as 5 - 2 and 15 - 2.

### Keywords

Subtraction - To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.

Minus - A synonym for subtract, represented by the symbol -

Difference - The result of subtracting one number from another. How much one number differs from another.

### 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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