Subitizing, a funny-sounding word, but a very important skill for developing number sense. Basically, we subitize when we instantly recognize a small group of objects as a number. For example, if I hold up five fingers and you instantly know it’s five without counting, you have subitized. This ability to move away from counting objects one-by-one is an important component of early numeracy. But did you realize that there are actually stages that students progress through as they develop subitizing skills?
Last year, when working with my Kinder babies, I noticed that most of them could recognize single groups of objects, such as the ones shown below.
These students were exhibiting the ability to engage in perceptual subitizing. They could subitize small groups of objects, typically up to 5, and state the number. This is an important first step! If your kiddos struggle with perceptual subitizing, flashcards for them (like the ones above) showing different representations of small groupings to 5. Also, check out this blog post for an easy little game for subitizing the dot patterns on a number cube you can download for free.
When shown a card with two subgroups (example below), however, many of my students could only state the two subgroups (3 and 2), but not combine the subgroups to state the total shown (5). Which brings me to conceptual subitizing.
Conceptual subitizing involves not only recognizing the subgroups, but also combining them together to compose a whole. To help move my students toward being able to combine the subgroups, I began showing them cards with the subgroups plus just one more. After they could state the total for the subgroup plus one more, I added in cards that showed the subgroup plus two more.
I created a deck of over 140 cards that can be used to gradually develop students’ subitizing skills. The cards show dice patterns, finger patterns, tally marks, ten-frames, and random dot patterns for sums up to 10 (5 and 5). Best of all? There’s now a digital version as well! I’m excited to hear how this gradual approach works for your students!