Subitising

We often recognise the number associated with a particular pattern straight away, even before we have had time to "count" the items.

The process of immediately recognising how many items are in a small group is called subitising. This name comes from the Italian word subito, which means "immediately" or "right now". When playing a game with dice we normally recognise the number of dots immediately.

By "chunking" information, subitising contributes to early forms of grouping. The process of subitising can also be used with seeing parts in the whole.

If you look at the dot pattern for five you become aware of seeing it also as four and one, or three and two. Domino patterns capture this idea of subitising playing an advanced-organising role. People can see each side of the domino as four individual dots and as "one four". They see the domino as composed of two groups of four and as "one eight".

The notion of units within units is important for separating and combining numbers as well as for multiplication, division and measurement. Subitising contributes to part-whole (sometimes called part-part-whole) number relations.

Can you see the three,
the two and the five?

Interpreting number in terms of part-whole relationships makes it possible for children to think about a number as being made up of other numbers.