NA1-5: Generalise that the next counting number gives the result of adding one object to a set and that counting the number of objects in a set tells how many.

Elaboration on this Achievement Objective

This means students will understand the link between the cardinal and ordinal aspects of counting. The ordinal aspect refers to the fact that counting numbers have a conventional order. The last number in a count tells how many objects are in a set if all the objects are matched in one-to-one correspondence to the sequence of counting numbers. The next number in the counting sequence tells the result of adding an object while the number before in the sequence tells the count when an object is removed. The cardinal aspect involves knowing that when counting a set of items the last number describes all the items in the set, no matter their colour, size, arrangement or other attributes. This count can be trusted and built upon.