Subitizing Dots

Introduction

Dr. Douglas Clements, in an article written in the March 1999 Teaching Mathematics Journal wrote,

"Children who can not subitize conceptually are handicapped in learning such arithmetic processes." (p. 401)

The arithmetic processes Dr. Clements is most likely referring to are: addition, subtraction, multiplication, and division.  Students who can subitize numbers can see how many are in a set instantly.  This ability, as Clements suggests, will help students eventually solve problems such as 3 + 9 = 12 because they will have had practice composing and decomposing groups of 3 and of 9 (e.g. 3 = (2+1), (3+0), (1+1+1) and 9 = (1+8), (2+7), (3+6) etc.).

Let's see if you can subitize.  How many dots do you see in figure 1?

Figure 1

There are 3 dots displayed and it is highly unlikely that you had to count each dot to determine the quantity.  You instantly saw 3 dots and this instantaneous "seeing" is called subitizing.

Teacher Problem

So, what if you are in a classroom where many children have not developed their subitizing skills?  How would you develop them?  Well, one way is to play the "Show and Tell game" (MacDonald & Shumway, 2016, p. 345).  In this subitizing game, a teacher shows a student a "card" with a number of dots on it and the student tells the teacher how many dots they see as quickly as possible.

Here is an example of the game.

1.) Teacher shows the student this "card":

2.) Student tells the teacher they see 4 without having to count: 1, 2, 3 4 - they just "see a group of 4."

Teacher Solution

Create your own subitizing cards using Google Slides.  Take a look at this example by elementary school teacher Jake Jaroszewski.

Here is a link to Jake's Subitizing Dot Cards

One of the great things about Google Slides is that you can share your work with others, they can make a copy of it and then modify it to suit their needs.

Teachers can use these cards in a digital format or print, laminate and share them with their students to help them develop subitizing skills and increase their confidence in math.

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Resources

Clements, D. H. (1999). Subitizing: What Is It? Why Teach It? Teaching Children Mathematics, 5(7), 400–405.

MacDonald, B. L., & Shumway, J. F. (2016). Subitizing Games: Assessing Preschoolers’ Number Understanding. Teaching Children Mathematics, 22(6), 340.