What is subitizing? Have you ever noticed how quickly you can recognize the number of fingers someone is holding up? Or how many dots there are on a die? That’s subitizing (soo-bi-tiz-ing)! And it’s a critical foundational skill. This blog will cover everything you need to know about what it is, why it’s important, practical tips for implementation, and how it relates to word problem instruction.

What is subitizing?

Subitizing is the ability to see a small collection of objects and instantly know how many there are without counting. It’s derived from a Latin word that means suddenly. There are two types: perceptual and conceptual.

Perceptual subitizing

Perceptual subitizing is knowing (or perceiving) how many objects are in a set of 5 or less. There are even some early studies that suggest infants and some animal species have the innate ability to ‘see’ small groups of objects without needing mathematical processes to figure out how many. It feels instinctual but it isn’t for everyone.

Conceptual subitizing

Once groups have 6 or more objects, it’s not possible for the brain to ‘see’ how many  without using some type of mathematical process. This is where conceptual subitizing comes into play. 

Our brains have to decompose (or break down) larger sets into more manageable groups and then compose them again to form the whole set. For example, a group of 6 might be decomposed into a group of 4 and a group of 2 so the brain can process it and recognize the value. It builds upon the ability to perceptually subitize.

Why is subitizing important?

There’s a wealth of research to support the idea that subitizing is a “‘fundamental skill in the development of students’ understanding of number” (Baroody 1987, 115). It:

• is a precursor to more sophisticated counting skills
• provides flexibility for students to solve addition and subtraction problems mentally
• allows students to visualize representations, a critical component of mathematics

If you’re not already familiar with subitizing (or even if you are), here are two amazing resources I encourage you to check out:

? Christina Tondevold (7:18 ) explains a bit more about the above ideas. She shares practical tips for implementation and has a free resource you can download. (If you’re already on my email list, you know I love providing free resources. If you’re not, you can subscribe below.)
? Graham Fletcher (7:34) explains the progression of early number and counting and how subitizing fits in.

How does subitizing help students with number stories?

Structures of Equality (SoE) focuses on helping students understand what is happening in number stories through the use of visual representations. But what happens when it’s time for computation?

I could tell you about it, but if a picture is worth a thousand words, this video of a 2nd grade classroom is priceless.
?  Valerie Faulkner (7:28) shows us how students can apply the work they’ve done with subitizing to solve for unknown values when using a bar model. (Since the structures are based on work with bar models, you’ll see how easily it can be applied to SoE)

Conclusion

Subitizing is a powerful skill students need to internalize to become proficient mathematicians. It paves the way for advanced mathematical concepts. Whether students struggle with counting or advanced problem-solving, the roots might be traced to this foundational number sense skill.

Interested in more practical tips and actionable advice? Join my Facebook community or subscribe to my email list. Subscribers get access to free resources before they’re available to anyone else.

“Exploring the Research on Subitizing.” Weebly. Retrieved March 2024, from https://subitizing.weebly.com/exploring-the-research.html

Richardson, K. (2012). How Children Learn Number Concepts: A Guide to the Critical Learning Phases. Math Perspectives Teacher Development Center. 

If you want to see more of Valerie Faulkner’s work, check out her website.