How do you change a singular noun to the plural form?

Answer 1

Most nouns add an S or ES.

Some nouns are both singular and plural (sheep) and others form nonstandard plurals (man-men, child-children).

Answer 2

To change a singular noun to its plural form, you typically add an -s, -es, -ies, or change the word entirely. For example, "cat" becomes "cats," "box" becomes "boxes," "lady" becomes "ladies," and "child" becomes "children."