Area formula
For a rectangle, area = length x width.
This works because a rectangle is made of rows of equal square units.
Year 6
Recognise when it is possible to use formulae for area and volume of shapes
Recognise when a formula can be used to calculate area or volume.
Lesson overview
Measurement
A formula is useful when a shape has a known rule for finding area or volume. Rectangles and cuboids are good examples because their dimensions fit a clear pattern.
Volume formula
For a cuboid, volume = length x width x height.
Volume counts cubic units in 3 dimensions.
Worked example
Can a 5 by 3 rectangle use a formula for area?
| Shape | Useful formula |
|---|---|
| rectangle | length x width |
- Identify the shape as a rectangle.
- Rectangles use the area formula length x width.
- Substitute 5 and 3 if you need the value.
- So yes, a formula can be used.
Try it
First identify the shape, then decide whether there is a known area or volume rule.
Question 1
Which formula gives the area of a rectangle?
Question 2
Which formula gives the volume of a cuboid?
Question 3
A rectangle 5 by 3 can use:
Question 4
A cuboid needs how many dimensions for volume?
Question 5
Which measurement uses cubic units?
| Measurement | Units |
|---|---|
| area | square units |
| volume | cubic units |
Common mistakes
Watch for these when working through the lesson.
- Using an area formula for a volume question.
- Trying to use a formula when the shape and measurement do not match.
- Forgetting which dimensions are needed in the formula.
Related topics
These ideas fit closely with this lesson.
- Calculate the area of parallelograms and triangles.
- Calculate, estimate and compare volume of cubes and cuboids.