We’re really getting back into the swing of things here on the Upper Test Side. Summer feels like a distant memory as our teachers swamp us with homework, projects, and tests. Trust me, if you’re already counting the days until Thanksgiving break, you’re not alone. And if you’ve got an ACT or SAT in the pipeline for this back-to-school season, you’re a better man/woman than I am.

I, your friendly neighborhood Grammar Girl, have been out and about in search of those sweet, juicy grammatical secrets — the ones that standardized tests hope you’ve forgotten since that one eighth grade English module. Today’s scoop is on the apostrophe, one of those classic sneaky little punctuation marks that you definitely know how to use. Or at least you kind of think you know. Wait, what’s an apostrophe again?

1. Possession

One of the most important jobs of an apostrophe is to show ownership of something.

For a singular noun, the apostrophe follows the first noun (the one doing the possessing):

The student’s latte is getting cold.

In this case, there is a student who owns a latte (which they better drink fast).

For a plural noun, the apostrophe follows the plural form of the first noun:

The students’ awkward silence made the teacher uncomfortable.

The apostrophe here follows the “s” in “students.” That’s how we know that the awkward silence belongs to more than one student.

The people’s favorite English guru is obviously Grammar Girl.

Why isn’t the apostrophe after the “s” here like it was in the last example? “People” is already plural, so it’s not necessary to put an “s” before the apostrophe.

Apostrophes are only used for possessive nouns, not possessive pronouns. If we want to make a pronoun possessive, we use its special form.

it – its

The last bell sure takes its own sweet time, doesn’t it?

she – her 

She forgot her calculator on test day.

he – his

His study habits were not the best.

who – whose 

Do you know whose latte that is?

they – their

They know their grammar rules inside and out.

2. Contraction

The other function of an apostrophe is to allow the smushing (obviously the official term) of words together. On the SAT and ACT, this only happens with pronouns and helping verbs.

They are – they’re

They’re over there!

You are – you’re

You’re aware that your backpack is open, right?

Who is – who’s

Who’s a good doggie? You’re a goo—ouch, stop biting me!

It is – it’s

It’s about time to stop talking about apostrophes.

One other type of contraction you may see is a helping verb combined with a negative. Those are easy.

Do not – don’t

Don’t even think about hitting that snooze button on test day.

Whenever you see an apostrophe in a word with a pronoun or a negative, just read it as two separate words. That way you won’t be tricked by answers that “sound right” but are still grammatically incorrect.

That’s pretty much it for apostrophes. Those slippery little squiggles up top aren’t super complicated, but the SAT and ACT are betting that you don’t know exactly how and where to use them. But won’t they feel lame when they see how much of a piece of cake apostrophe questions are to you now. I mean, come on.

You know you love punctuation rules.

X, O, X, and O,

Grammar Girl

P.S. Keep this on the DL, but if you’re looking for more test prep tips for grammar or even *gag* math, I just might be able to hook you up. Schedule a call with an academic advisor and tell them Grammar Girl sent you.