Grammarly
Grammarly Blog: Possessive Case of Nouns: Rules and Examples
This page expains the rules for forming possessive nouns and provides examples.
Khan Academy
Khan Academy: Advanced (Plural) Possession
Possessive plurals have a complicated relationship with apostrophes, but this exercise is here to help you understand it!
Other
Possessive Nouns Rules and Practice
Use these handy rules to help how to create a possessive form.
English Zone
English Zone: Basic Possessives 1
This site offers a 10 question quiz in with fill-in-the blank statements and three choices of possessive noun spellings. Make your choice and find out the correct answer.
Soft Schools
Soft Schools: Possesives Examples
Resource provides an explanation and examples of possessive nouns.
ClassFlow
Class Flow: Nouns Review
[Free Registration/Login Required] This flipchart can be used as a review and assessment of nouns or as a way to introduce nouns. It covers what a noun is, common/proper nouns, singular/plural nouns, and possessive nouns.