# Evaluating expressions with and without changing the subject

I can evaluate an expression where the subject has been changed and where it has not.

# Evaluating expressions with and without changing the subject

I can evaluate an expression where the subject has been changed and where it has not.

## Lesson details

### Key learning points

- Changing the subject can make it easier to evaluate a formula.
- It is possible to evaluate a formula without changing the subject.
- Both forms of the formula give the same result.

### Common misconception

Changing the subject of an equation or formula is only done when you are told to.

Having students practise rearranging before substituting and vice versa allows them to decide when the skill could be useful.

### Keywords

Subject of an equation/formula - The subject of an equation/a formula is a variable that is expressed in terms of other variables. It should have an exponent of 1 and a coefficient of 1.

### 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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