Number sense is a much deeper understanding of numbers and counting than simply counting from memory. Number sense involves realizing that a certain spoken number represents a certain quantity; it is understanding that 6 is smaller than 8 and larger than 4. Number sense is not innate, it must be taught. Before delving into activities to teach number sense, a general awareness of the development of number sense is important.

Number sense goes through these four broad stages: perceptual quantification, one to one correspondence, cardinality, and subitizing.

Perceptual Quantification

This first level of number sense, perceptual quantification, is innate. If you have a pile of 10 cheerios and ask a young child is asked to grab a specific quantity (i.e., 10 cheerios), they will grab a handful that looks like the amount shown. They are relying solely on visual discrimination and do not have any concept of what “ten” means.

One to One Correspondence
The second level of number sense is not innate, and it is the step that parents and teachers must begin teaching children. One to one correspondence in a general sense is the ability to match each part of one set to an equal number in another set, for example, matching up five toy lady bugs with five toy flowers. One to one correspondence in a strictly math sense is the understanding that one counting word is paired with one object.

Cardinality
Cardinality, simply put is understanding how many are in a set. Furthermore, it is knowing that each number represents a quantity, and whatever number you stop counting at is the quantity of the entire set. Cardinality also refers to the idea that each number means a specific amount and no matter what you do to the objects in the set to rearrange them there is still the same amount of objects. Cardinality, much like one to one correspondence, must be taught.

Subitizing
Subitizing is when a person can instantly recognize the number of objects shown without actually counting them, for example, the dots on a dice. It’s an automatic recognition. Subitizing is important because it provides a basis for early addition.

The great news about number sense is that it is teachable! Teachers (and parents) can set up specific activities to facilitate the development of each of the areas of number sense. Many aspects of number sense are taught through daily routines and play.