Plural Possessives

Plural possessive nouns show plural nouns owning, or possessing, something.
girls' pencils (the pencils that belong to the girls)
birds' nests (the nests that belong to the birds)
penguins' chicks (the chicks that belong to the penguins)

Remember, to make a noun possessive, first write the noun, then add an apostrophe to the end.
I want to write a sentence about the shoes that belong to the boys.
First, I write the word boys, because there are several boys, and they all have shoes.
Then, I add an apostrophe to the end of the word to make it boys'.

Here are more examples:
students' desks (the desks that belong to the students)
families' picnic (the picnic that belongs to the families)
dogs' fur (the fur that belongs to the dogs)

Be careful!:
It's easy to be tricked when you are making an irregular plural noun possessive.
Remember, write the noun first, then add an apostrophe to the end, and then add an -s only if there isn't one.

Incorrect: childrens'
This is incorrect because childrens is not a word!

Incorrect: familie's
This is incorrect because familie is not a word!

The singular or plural noun needs to be complete before you add an apostrophe to the end. Look at these examples:
children's music (the music that belongs to the children)
dogs' leashes (the leashes that belong to the dogs)
women's restroom (the restroom that belongs to the women)

women's rights (the rights that belong to the women)
children's playground (the playground that belongs to the children)
men's room (the room that belongs to the men)

Incorrect: The familie's all had fun at the festival. ("all" does not belong to "families," and you cannot break up a word with an apostrophe)
Incorrect: Dog's are great pets. ("are" does not belong to "dog")
Incorrect: Everyone likes to relax on the weekend's. (nothing belongs to "weekend")