Apostrophes and possessives on ACT English: using an apostrophe for possession (singular adds 's, plural ending in s adds just an apostrophe) and for contractions, distinguishing its from it's and whose from who's, and rejecting the apostrophe in a plain plural that shows no possession.

What this skill is asking

The apostrophe does two jobs, possession and contraction, and the ACT tests whether you can tell them apart and whether you can form possessives correctly. The traps are predictable: "its" versus "it's", a plain plural that should not have an apostrophe, and singular versus plural possessives. Because the rules are mechanical, this is one of the most learnable point sources on the section.

The two jobs of an apostrophe

Every apostrophe question comes down to which job is in play.

Its, it's, whose, who's

The pronoun pairs are the most tested apostrophe trap, because the possessive form is the one without the apostrophe, the reverse of how nouns work.

This expansion test resolves nearly every pronoun-apostrophe question in seconds. "The team lost it's lead" expands to "the team lost it is lead", which is nonsense, so the possessive "its" is correct.

Singular versus plural possessive

When possession is clearly meant, the remaining decision is how many owners, which sets where the apostrophe goes.

Why apostrophe questions are reliable points

These questions reward a fixed decision tree: possession, contraction, or plain plural. The expansion test handles the pronoun pairs, the owner count handles singular versus plural, and the "no apostrophe in a plain plural" rule handles the rest. Because the answer is determined by rule rather than feel, careful application earns the point every time. The skill also supports pronoun case (possessive pronouns) and subject-verb agreement (a plural subject with no apostrophe still needs a plural verb).

Try this

Q1. How do you decide between "its" and "it's", and between "whose" and "who's"? [Recall]

• Cue. Expand the contraction: if "it is" (or "it has") fits, use "it's"; if "who is" (or "who has") fits, use "who's". If the expansion does not fit and you mean possession, use the apostrophe-free possessives "its" and "whose".

Q2. A sentence reads "The teachers cars filled the lot" and means the cars belonging to several teachers. How should it be punctuated, and why? [Short explanation]

• Cue. "The teachers' cars filled the lot." Possession is meant (the cars belong to the teachers), and there is more than one teacher, so the plural "teachers" (ending in s) takes only an apostrophe after the s: "teachers'". "Cars" stays a plain plural with no apostrophe.