Progression in understanding units of measure

Stage 1

Awareness of what attribute is being measured and of associated language.

Children need to be aware of what characterises the length of an object as opposed to its mass or volume. They need to learn the vocabulary of measures, for example long, short, heavy, light, large, small etc.

Look at my big box!

My box is light! Sammy

Snake is very long!

Stage 2Direct comparison of 2 entities, more than 2

entities, then ordering

At this stage, children learn to compare two or more objects using appropriate comparative language vocabulary. Once children can directly compare objects, they can learn how to order a set of more than two objects, for example from longest to shortest.

The grey pencil is longer than the white pencil!

I’ve ordered my towers

from shortest to

tallest!

Stage 3Allocating numerical values to one quantity in

relation to another.

At this stage, children learn to quantify the degree of comparison.

Sammy Snake is about 3 times as

long as Billy Bear!

Stage 4Indirect Comparison: Use of arbitrary units.

At this stage, children learn to compare their objects against one arbitrary unit, for example they could measure their height or the length of the

room in spans or cubits or footprints. Everyday items can also be used as the arbitrary unit, for example shoes or pencils or toy cars.

Our classroom is about 30

footprints wide!

Miss! The table is

about 10 pencils long.

Stage 5

Use of non-standard units

Non-standard units are ‘units’ which are all of identical magnitude, for example 2p coins, cotton reels, playing cards, straws and Cuisenaire rods.

It now becomes possible to numerically compare the size of objects.

Billy Bear is one straw long and Sammy Snake is three straws long so Sammy Snake is 2 straws longer than Billy Bear. That’s also three times

as long Sir!

Stage 6

Use of standard units

The transition to standard units involves recognising the need to use a common unit of measure that everybody can use to compare the size of objects.

These multilink cubes are 1cm long

so the shortest tower is 3cm and the longest is 7cm

long!

Stage 7

Use of subsidiary units

In some cases the standard unit of measure is too accurate or not accurate enough. Thus a range of units which are multiples or subdivisions of the standard unit can be introduced. Along with this comes the following areas of work:

• Relationships between units, for example: 1000 mm = 100 cm = 1m.

• Decimal notation, for example: the classroom is 8.4 m long!

• Making appropriate choices of units, and hence, measuring devices, for example: I need to use a metre rule to measure the classroom!

Stage 8

Conversion of units

The final stage introduces conversions:

1. Between metric units.

2. Between metric and imperial units.It is 240 km from

Calais to Paris. Um . . . 240 divided by 8 equals 30. 30 x 5 =

150. So it is 150 miles from Calais to

Paris!