What is Subitizing?

While familiarizing myself with the changes to our primary school Math curriculum I came across the term 'subitizing' in Mathematics. Naturally I had to do a little research to begin to understand what it is all about. Quite simply I came to the realization that this is nothing new. Subitizing is knowing what an amount is without counting. By simply looking at patterns or the arrangement of the shapes one can immediately tell how many there are in the set. It's like looking at the dots on a di and knowing how many there are without even counting. That is what we call 'subitizing'!

The term 'Subtizing' was coined in 1949 by Kaufman, Lord, Jensen, Reese, & Reese and Volkmann in the article entitled, 'The Discrimination of Visual Number'. In this article Subitizing is explained as the effortless and quick identification of the number of items in a set of objects (the cardinality of the set) if the set has four or fewer items. 

 

 

At a glance you are able to quickly and effortlessly tell the amount represented in each set based on the visual pattern or the spatial arrangement of the dots. However, subitizing becomes more difficult for numbers greater than four.because of the difficulties in grouping the elements.

 


In the sets above the spatial arrangement of the dots will most likely be a little more challenging for preschool kids. In that case they will either look for the familiar one-to-four arrangements or resort to one-by-one counting to solve.

I have found that the subitizing of numbers one to four is extremely important in early math literacy. As such greater attention is needed to this foundation skill and that once taught properly learning to recognize greater sets would be far easier to accomplish.


For more indepth information on the basics of subitizing go to University of Buffalo Website (PDF link).


Free Pretty Black and White Dice Clip Art Set

Free Heart Shaped Subitizing Cards