SAT Grammar Rules: The Punctuation and Usage Rules You Need
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SAT grammar questions fall under Standard English Conventions and test a small, predictable set of rules: how to join and separate clauses, when to use semicolons, colons and dashes, apostrophes, subject-verb and pronoun agreement, verb tense and modifier placement. Learning these rules is one of the fastest ways to gain Reading and Writing points.
Start with independent clauses
An independent clause has a subject and a verb and can stand alone as a sentence: "The students finished the test." A dependent clause cannot: "Because the students finished the test." Most punctuation questions depend on whether the pieces on each side of the punctuation are independent clauses.
Joining two independent clauses
A period and a semicolon do the same job between two independent clauses. If two answer choices differ only by period versus semicolon, neither is the answer.
| Method | Example | Correct? |
|---|---|---|
| Period | The test ended. Everyone cheered. | Yes |
| Semicolon | The test ended; everyone cheered. | Yes |
| Comma + and, but, or, so, for, nor, yet | The test ended, and everyone cheered. | Yes |
| Colon, when the second part explains the first | The result was clear: everyone passed. | Yes |
| Comma alone (comma splice) | The test ended, everyone cheered. | No |
| Nothing (run-on) | The test ended everyone cheered. | No |
Semicolons, colons and dashes
- Semicolons join two independent clauses or separate list items that already contain commas: Austin, Texas; Denver, Colorado; and Miami, Florida.
- A colon must follow a complete sentence. "She brought three things: a calculator, a pencil and a snack" is correct; "She brought: a calculator" is not.
- Extra information is set off by a matching pair of commas, dashes or parentheses. If it opens with a dash, it must close with a dash.
- Test it: remove the extra information. The sentence should still be complete.
Commas that do not belong
- No comma between a subject and its verb: "The results of the study were surprising."
- No comma between a verb and its object.
- No commas around an essential name: "The novelist Toni Morrison won the Nobel Prize."
Apostrophes
- Singular possessive: the student’s book. Plural possessive: the students’ books.
- Its is possessive; it’s means it is.
- Their is possessive; they’re means they are; there is a place.
Agreement, tense and modifiers
- Subject-verb agreement: the verb agrees with its subject, not the nearest noun. "The list of required materials is posted online."
- Pronoun agreement: "Each team submitted its project." A team is singular.
- Verb tense: match the timeline of the surrounding sentences unless something signals a change in time.
- Modifiers: an opening phrase must describe the noun right after the comma. "After studying for weeks, Maria found the test easy," not "the test seemed easy to Maria."
A four-step process for every grammar question
- Look at what changes across the answer choices.
- Name the rule being tested.
- Find the key words: the subject, the clauses on each side of the punctuation, or the noun a pronoun replaces.
- Eliminate choices that break the rule and confirm the one that remains.