Counting a collection is to list all its objects without forgetting any and without counting some twice.
A number is an abstract concept that defines a quantity. It does not depend on the nature of the items counted nor the order of counting.
A number is written from 10 symbols, called numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, 9).
Counting can be done by identifying the objects one by one, or by grouping them in packages.
This animation allows you to introduce these different concepts: