SAT grammar rules: the cheat sheet for Standard English Conventions
TutorAura guide · Updated
Grammar questions on the Digital SAT come from the Standard English Conventions domain of the Reading and Writing section (College Board). They test a small set of rules again and again, which makes them some of the quickest points to gain: learn the rules below, practise spotting them, and these questions take well under the 71 seconds you have on average.
Each question shows a short passage with a blank and four ways to fill it. Read the whole sentence, decide what the sentence needs, then choose.
Key takeaways
- Most questions are about where one sentence ends and the next begins.
- A comma alone can't join two complete sentences; a period, semicolon or comma + and/but/so can.
- A colon must follow a complete sentence.
- Match verbs to their real subject, and pronouns to the noun they replace.
1. Joining two complete sentences
A complete sentence (independent clause) has a subject and a verb and can stand alone. Two of them can be joined in only a few ways:
| Correct | Example |
|---|---|
| Period | The study was small. Its results were surprising. |
| Semicolon | The study was small; its results were surprising. |
| Comma + and, but, or, so, yet, for, nor | The study was small, but its results were surprising. |
Wrong: The study was small, its results were surprising. That's a comma splice. Also wrong: nothing at all between them (a run-on).
2. Transitions like however and therefore
Words such as however, therefore, moreover and for example don't join sentences on their own. Between two complete sentences, they need a semicolon or period before them and usually a comma after:
The results were promising; however, the team needed more data.
Wrong: The results were promising, however, the team needed more data. (comma splice)
3. Colons and dashes
- A colon must come after a complete sentence. It introduces a list, an explanation or an example: The garden needed one thing: rain.
- Wrong: The garden needed: rain. (what comes before the colon isn't a complete sentence)
- A pair of dashes works like a pair of commas around extra information: The bridge, finished in 1932, is still in use can also be written with a dash on each side of finished in 1932. Use two dashes or two commas: don't open with a dash and close with a comma.
4. Commas around extra information
If information can be removed and the sentence still makes sense, put commas on both sides:
The novelist, who grew up in Lagos, writes about migration.
If the information is needed to identify the noun, use no commas: The novelist who won the prize spoke first. And never put a single comma between a subject and its verb: The results of the survey were clear (no comma after survey).
5. Apostrophes: possession and plurals
| Form | Example |
|---|---|
| Singular possessive | the student's notes |
| Plural possessive | the students' notes |
| Irregular plural possessive | the children's books |
| its (possessive) vs it's (it is) | The company changed its logo. It's new. |
| their / there / they're | Their results are there; they're impressive. |
Plurals never take an apostrophe: the researchers found, not the researcher's found.
6. Subject–verb agreement
The verb must match its real subject, which may be far from it. Cross out phrases in between:
The list of required materials is long. (the subject is list, singular)
Each of the studies was peer reviewed. (each is singular)
When two subjects are joined by and, the verb is plural: The chemist and the physicist were awarded the prize.
7. Pronouns, verb tense and modifiers
- Pronouns must agree with the noun they replace: The team presented its findings (one team). The scientists presented their findings.
- Verb tense should fit the time shown in the passage. If the passage describes 1902 in the past tense, keep it there.
- Modifiers must sit next to what they describe: Walking to school, Maya saw the eclipse, not Walking to school, the eclipse was visible.
Practise until it's automatic
Knowing a rule isn't the same as spotting it in 30 seconds. Practise in short sets, check every answer, and write down the rule behind each mistake. Then test yourself in timed conditions: our free Reading and Writing practice test has two adaptive 32-minute modules with every answer explained. For the other question types, see SAT Reading and Writing tips.
Frequently asked questions
What grammar is on the SAT?
Mostly sentence boundaries (periods, semicolons, commas with conjunctions), colons and dashes, commas around extra information, apostrophes, subject–verb agreement, pronoun agreement, verb tense and modifiers.
Can a semicolon replace a comma on the SAT?
Only between two complete sentences. A semicolon works like a period: both sides must be able to stand alone.
How many grammar questions are on the SAT?
Grammar questions belong to the Standard English Conventions domain, which makes up roughly a quarter of the Reading and Writing section.
Is 'however' a conjunction?
No. Between two complete sentences, 'however' needs a semicolon or period before it, not just a comma.
Sources
- Assessment Framework for the Digital SAT Suite. College Board.
- Digital SAT Sample Questions and Answer Explanations. College Board.
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