1. Using the Apostrophe
An apostrophe is used to form contractions, to form plurals, or to show possession.

2. Forming Plurals
Use an apostrophe and s to form the plural of a letter or a numeral.
I received three A’s on my report card.
I scored three 10’s in a row on my quizzes.

3. Forming Plurals
WAIT!
There is, of course, an exception to this rule when dealing with dates.
1950s vs. ’50s
Note that in the first example, there is no apostrophe. The second example uses an apostrophe to show an omission of the first part of the year.

4. Forming Singular Possessives
To form the possessive of most singular nouns, add ‘s.
Last weekend I saw Denzel’s new movie.
We needed someone to fix the building’s leaky roof.

5. Forming Singular Possessives
When a singular noun with two or more syllables ends with an s or a z sound, the possessive may be formed by adding just an apostrophe.
Luis’ honesty convinced me he did not cheat.
Odysseus’ courage is an admirable trait.

6. Forming Plural Possessives
To form the possessive of most plural nouns ending in s, add just an apostrophe.
I spent all night correcting my students’ exams.
The boys’ basketball team won their first game.

7. Forming Plural Possessives
For plural nouns not ending in s, add ‘s.
I needed the children’s clothing sizes before I went shopping.
The men’s room is upstairs on your right.

8. Forming Compound Noun possessives
Form the possessive of a compound noun by placing the possessive ending after the last word.
The secretary of state’s speech was very powerful.
My brother-in-law’s birthday is in February.

9. Forming the Possessive of an Indefinite Pronoun
Form the possessive of an indefinite pronoun (each, everyone, no one, anyone…) by adding ‘s.
Somebody’s smelly sneakers are stinking up the hallway.
I need everyone’s paper at the beginning of class.

10. Showing Shared Possession
Add ‘s to the last noun when the possession is shared.
Huey, Dewey, and Louie’s house is on the market.
If possession is not shared, add ‘s to each noun.
Huey’s, Dewey’s, and Louie’s houses are on the market.