Overview
Apostrophe questions are among the most frequently tested punctuation items on the Digital SAT. The SAT tests exactly two legitimate uses of the apostrophe: marking possession (ownership) and forming contractions. Apostrophes are never used to create ordinary plural nouns. Most questions hinge on selecting the correct form from a set of look-alike options — for example, choosing between “its,” “it’s,” “its’,” or “its’s.”
Key Points
2.1 The Two Legitimate Uses of Apostrophes
| Use | Example | Notes |
|---|---|---|
| Possession | the student’s essay | Marks ownership |
| Contraction | it’s (= it is / it has) | Marks omitted letters |
| NOT for plurals | many hawks (NOT hawk’s) | Never add ’ to form a plural |
2.2 Forming Possessives: Singular, Plural, and Irregular
Singular nouns — always add ‘s regardless of the noun’s ending:
- the dog → the dog’s leash
- the class → the class’s rules (though the SAT avoids this edge case)
Plural nouns ending in -s — add apostrophe only (after the s):
- the students → the students’ papers
- the doctors → the doctors’ offices
- the teachers → the teachers’ lounge
Irregular plural nouns (do NOT end in -s) — add ‘s:
- children → the children’s playground
- men → the men’s team
- women → the women’s decisions
- people → the people’s choice
Rule of thumb: If the base plural word does not end in -s, treat it like a singular and add ‘s.
2.3 The Four Critical Confusable Pairs
These four pairs are the most tested apostrophe items on the Digital SAT. Memorize both members of each pair.
| Contraction (apostrophe) | Meaning | Possessive / Other (no apostrophe) | Meaning |
|---|---|---|---|
| it’s | it is / it has | its | belonging to it |
| they’re | they are | their | belonging to them; there = location |
| you’re | you are | your | belonging to you |
| who’s | who is / who has | whose | belonging to whom |
Substitution Strategy: Replace the word in question with the expanded form of the contraction. If the sentence still makes sense, use the contraction (with apostrophe). If not, use the possessive/other form (no apostrophe).
- “The committee released [it’s / its] report.” → Substitute “it is”: “The committee released it is report.” Does not make sense → use its.
- “[It’s / Its] raining today.” → Substitute “it is”: “It is raining today.” Makes sense → use it’s.
2.4 Possessive Pronouns — NEVER Use an Apostrophe
The following pronouns are already possessive and never take an apostrophe:
its, hers, his, ours, theirs, yours, whose
Common wrong forms you will see as trap answers: her’s, their’s, your’s, who’s (when possessive is needed).
2.5 Joint vs. Separate Possession
| Situation | Form | Example |
|---|---|---|
| Joint (shared item) | Apostrophe on last noun only | Ali and Sam’s project |
| Separate (each owns one) | Apostrophe on each noun | Ali’s and Sam’s projects |
2.6 Apostrophes and Decades
- Plural decade: the 1990s (no apostrophe)
- Possessive of a decade: the 1990s’ music (apostrophe after s)
Pitfalls and Common Mistakes
Pitfall 1 — Using an Apostrophe to Form a Plural Noun
Wrong: Many hawk’s circled the field. / The CEO’s of three companies met. Right: Many hawks circled the field. / The CEOs of three companies met.
Fix: Ask “Is this a plural (more than one) or a possessive (ownership)?” If it is simply more than one of something, no apostrophe is needed.
Pitfall 2 — Confusing “its” and “it’s”
Wrong: The dog wagged it’s tail. / Its raining outside. Right: The dog wagged its tail. / It’s raining outside.
Fix: Use the substitution test. Replace the word with “it is.” If the result is grammatically correct, use it’s. Otherwise use its.
Pitfall 3 — Confusing “whose” and “who’s”
Wrong: The author, who’s book won the prize, spoke at the event. Right: The author, whose book won the prize, spoke at the event.
Fix: “Whose” is the possessive of “who” and never has an apostrophe. Substitute “who is” — if it makes no sense, use “whose.” Remember: whose = ownership, who’s = who is / who has.
Pitfall 4 — Wrong Placement of Apostrophe in Plural Possessives
Wrong: The student’s papers were graded. (implies one student when context means many) Right: The students’ papers were graded. (many students → apostrophe after s)
Fix: Always check context for number first. Count the owners: one owner → ‘s; multiple owners (noun ending in -s) → s’.
Pitfall 5 — Treating Irregular Plural Possessives Like Regular Plural Possessives
Wrong: The childrens’ games were organized. / The womens’ conference was held. Right: The children’s games were organized. / The women’s conference was held.
Fix: Irregular plurals (children, men, women, people, oxen) do NOT end in -s, so treat them like singular nouns and add ‘s.
Pitfall 6 — Using Apostrophes with Other Possessive Pronouns
Wrong: The trophy was her’s. / The decision was their’s. Right: The trophy was hers. / The decision was theirs.
Fix: No possessive pronoun (his, hers, its, ours, theirs, yours, whose) ever takes an apostrophe. If you can replace the word with “belonging to [pronoun],” no apostrophe is needed.
Related Entries
- Punctuation_Commas
- Punctuation_Semicolons_Colons_Dashes
- Pronoun_Antecedent_Agreement
- Subject_Verb_Agreement
- Sentence_Boundaries
Quick Reference Card
| Situation | Correct Form | Example |
|---|---|---|
| Singular possessive | noun + ‘s | the student’s book |
| Plural possessive (ends in -s) | noun + s’ | the students’ books |
| Irregular plural possessive | irregular plural + ‘s | the children’s toys |
| Contraction | missing letters → ‘ | it’s (it is), who’s (who is) |
| Possessive pronoun | no apostrophe | its, hers, theirs, yours, whose |
| Plain plural noun | no apostrophe | many students, the 1990s |
| Joint possession | apostrophe on last noun | Ali and Sam’s car |
| Separate possession | apostrophe on each noun | Ali’s and Sam’s cars |
The substitution test (for it’s / its, who’s / whose, etc.): Expand → “it is” / “who is” → If it makes sense, use the contraction. Otherwise, use the possessive.