Subitizing is the ability to rapidly determine the quantity of a small group of objects without counting. Subitizing is a fundamental skill in a student’s development of number understanding. There are two types of subitizing; perceptual and conceptual.
Perceptual subitizing is the ability to recognize the quantity of a set without counting. It is the basis for counting and cardinality. For example, recognizing the pattern of five dots on a dice as "5".
Conceptual subitizing is seeing number patterns within a set (part—whole) and then determining the quantity by putting the number patterns together . For example, when shown a domino with a pattern of 8 dots/pips the observer may break the 8 dots into two groups of 4
Conceptual subitizing is the basis of number and operation sense. Dot representations can be regular and irregular. Regular representation show the dots as you would find them on a die or domino. Irregular representations group the dots in a variety of ways.
We are learning to construct and deconstruct numbers. How many ways can you use red and yellow counters to make 6? A next step will be writing corresponding number sentences (3+3=6, 4+2=6, etc)