Math PK-2

Cardinality

Factor Connections

Hover to see how Factors connect to Cardinality. Then click connected Factors to explore strategies related to multiple Factors.

Cardinality is understanding how many items are in a set. To do this, a student must first understand that each number in a count sequence represents a cumulative quantity, then the student learns that the last number represents the quantity of the set (e.g., counting to 10 means there are 10 items in the set).

Main Ideas

Children advance through developmental stages of number concept. First is Pre-Numeral-Knowers when they have no understanding of Cardinality. Next is Subset-Knowers with two categories:

  • One-Knowers: Understanding the concept of the number one; and
  • Two- and Three-Knowers: Understanding the concept of the numbers two and three, which typically happens slowly.
    After they have achieved Three-Knower status, students acquire knowledge of all the numbers they can count relatively quickly in comparison. At this point, children have advanced from Subset-Knowers to Cardinal-Principle-Knowers.

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