Measurement and units

I can choose units, read scales, change units and find perimeter and area.

For grown-ups: this lesson in words

Ages 7 to 11 · Maths

Length is how long something is. A pencil is about 15 cm long.
Mass is how heavy something is. An apple weighs about 150 g.
Capacity is how much something can hold. A cup holds about 200 ml.
Small things like these use small units: cm, g and ml.
Picture: About 15 cm: 1 pencil, about 150 g: 1 apple and about 200 ml: 1 cup.
Bigger things need bigger units. A door is about 2 m tall.
A pineapple weighs about 1 kg.
This bottle holds about 1 l.
To estimate, make a sensible guess. Compare with things you know, like these.
Picture: About 2 m: 1 door, about 1 kg: 1 pineapple and about 1 l: 1 plastic bottle.
Your turn: Here is a bed. About how long is a bed?
Picture: 1 bed.
Choose one:
- 2 cm
- 2 m
- 20 m
Answer
The answer: 2 m
About 2 m.
A bed is about as long as a door is tall.
Picture: About 2 m long: 1 bed and about 2 m tall: 1 door.

mass:

How heavy something is. We measure it in g and kg.

capacity:

How much a container can hold. We measure it in ml and l.

estimate:

A sensible guess, made by comparing with something you know.

perimeter:

The distance all the way round the edge of a shape.

area:

How much flat space a shape covers. Count the squares inside.

This is the first part of the lesson. Grown-ups can unlock every lesson in the grown-ups area.