A young boy at a beach, encountering two adult Canada geese and a large number of fluffy goslings.

At the age of 2 or 3, a child will typically have learned the rules for regular plurals, and will apply those rules consistently, for instance by saying “gooses” as the plural of goose. By the age of 4 or 5, the child is likely to have learned common irregular plurals such as geese. (Photo courtesy of Ruth Hartnup on Flickr. License: CC BY.)

Photo courtesy of Ruth Hartnup on Flickr. License: CC BY.