SAT / ACT Prep Online Guides and Tips

The 12 SAT Grammar Rules You Must Know

author image
Posted by Justin Berkman | Feb 20, 2016 8:30:00 AM

SAT Writing



The SAT Writing and Language section is comprised of questions that test your knowledge of grammar and writing style. By learning the grammar rules that are tested on SAT Writing, you'll be preparing yourself to do exceptionally well on the Writing section, and you'll be one step closer to getting your target score. In this article, I'll explain the most important SAT grammar rules and provide related examples from the official practice tests.


How to Use This Guide

The SAT Writing and Language section tests you on a multitude of grammatical rules. Based on the content of the practice tests released by the College Board, many of these grammatical rules are likely to be tested on every SAT.

In this guide, I'll provide explanations and examples for the grammar rules that are tested most often on the SAT. In addition to the grammar questions, there are also writing style questions that make up a significant portion of the SAT Writing and Language section. You need to prepare for those questions, too.

The information in this guide will be extremely beneficial to you, especially if you're trying to get a middle score, starting your SAT Writing studying, or you're reviewing the most important SAT grammar rules.

If your target score is above a 700 for Writing and Reading, you should also thoroughly study the rules that are only rarely tested on the SAT.

Because this new version of SAT Writing is very similar to ACT English, I'm linking each rule to our corresponding ACT English article that provides more explanation of the rule, real test examples, and related rules that will help you do well on the SAT Writing section.


The Grammar Rules You Must Know for SAT Writing

Here are the 12 SAT grammar rules that you need to learn and understand before test day.


#1: Select the Correct Word Based on the Context of the Given Sentence

Word choice questions are common on the SAT. A word will be underlined, and based on the context, you have to select the best word to complete the sentence. These questions can be difficult because they require knowledge of vocabulary. There are two common types of word choice questions.


Type #1: Homophones

Homophones are words that sound the same but have different meanings. Here are some examples of homophones that have appeared on the practice SATs: fare/fair, cite/sight/site, then/than, there/their/they're, and its/it's. You should know what each of these words means and how it's used.


SAT Example


The sentence is comparing the cafe to a fair. Based on the context, the word "fair," which means an exhibition, usually with food and entertainment, is correct. There are multiple meanings of the word "fare," but it often refers to the money you pay for transportation, as in "bus fare." Clearly, the word "fare" doesn't make sense in this context, so you can immediately eliminate answer choice C.

Next, we need to determine if we should use "then" or "than." You use the word "than" to make comparisons and "then" to refer to time. Because the sentence is comparing the cafe to a fair, the correct answer is B.




Type #2: Related Words

The second type of word choice error involves synonyms or related words. A word will be underlined and the answer choices will be related words. However, only one word will be correct given the context of the sentence.


SAT Example



For these types of questions, I like to quickly go through each choice to see which one makes the most sense given the context. Based on the context of this sentence, we're looking for a word that indicates that the officials gave permission for the cat paintings to be made.

The word "forced" sounds too strong in this context, and generally, you don't "license" a painting to be made. The word "decreed," which means to order or command, also seems too harsh given the context. The word "commissioned" can mean hiring an artist to create a work. It's the only word that's typically used with artwork, and it's the most appropriate word for this sentence. The correct answer is B.

It's difficult to prepare for these questions because you don't know the specific words that will appear on the SAT. However, I recommend using the word choice questions on the practice SATs to help you study. Also, try to identify the subtle differences in the meanings of the words in the answer choices to help select the best word to complete the sentence.


#2: Use the Fewest Words Possible

Typically, the shortest grammatically correct answer choice that expresses the same information as the original sentence will be the right answer. Shorter sentences are more concise and easier to understand. On the SAT, words or phrases may be unnecessarily added to a sentence. Here's an example sentence with a redundancy error:

Every year, Jane runs the Los Angeles Marathon annually.

In this sentence, the word "annually" means that she runs the marathon every year. Because the sentence starts with "every year," the word "annually" is unnecessary. It doesn't add any new information to the sentence, and it should be eliminated.

Here's another example of a wordy sentence:

George is a person who is angry in nature.

This is a corrected version of the sentence:

George is an angry person.

The corrected sentence conveys the same information as the original but in a much more concise manner.



Justin Jackson/Flickr


SAT Example


Answer choices A, B, and C are redundant. The phrase "and other countries" already implies that there are other items on the list. The correct answer is D.


#3: Use the Correct Idiomatic Expression

Idiom questions can be challenging because they don't conform to specific rules. You have to rely on your knowledge of specific phrases and standard English conventions to answer these questions correctly. In most idiom questions on the SAT, you'll be asked to determine which preposition to use in a given sentence. Check out this example sentence with a prepositional idiom error:

Incorrect: After getting suspended, Herbert decided to focus at improving his behavior.

Correct: After getting suspended, Herbert decided to focus on improving his behavior.

There is no rule to learn to help identify this error, but the correct expression is "focus on."


SAT Example


The correct expression is "as a means of," and the answer is B. Study the idiom questions from the practice SATs, and review my article on SAT idioms to prepare yourself.





#4: Keep Verb Tenses Consistent

The general rule regarding verb consistency is that verbs should remain consistent in tense or form throughout a sentence. Here's an example of a consistency error:

Last week, Frank rented a car and drives to Las Vegas.

The verb "drives" should be in the past tense. Not only should "drives" be consistent with the past tense "rented," but also the phrase "Last week" indicates that this was something that happened in the past. This is the corrected version of the sentence:

Last week, Frank rented a car and drove to Las Vegas.

Also, on the SAT, the verb tenses of surrounding sentences can provide context clues for the proper tense to use in a given sentence to maintain consistency. Here's another example of a consistency error:

Trenton lives in a rural area. He enjoyed the peace and quiet.

The shift from the present tense "lives" to the past tense "enjoyed" doesn't make sense in context. Here is a corrected version of the sentence:

Trenton lives in a rural area. He enjoys the peace and quiet.


SAT Example


In this sentence, the verbs "is" and "serves" indicate that the underlined verb should be in the present tense. Answer choices B and D are not present tense verbs. Answer choice A is wrong because the "it" is redundant. The correct answer is C.


#5: Surround Non-Restrictive Clauses and Appositives With Commas

The SAT tests a number of comma rules, and these are two that you need to know.

Relative Clauses: Restrictive vs. Non-Restrictive

Relative clauses are dependent clauses that describe a noun and start with a relative pronoun or adverb like "who," "that," "which," or "where." The basic rule is that restrictive clauses shouldn't be surrounded by commas and non-restrictive clauses should be.


What's a Restrictive Clause?

Restrictive clauses are necessary to the meaning of the sentence. You can't take a restrictive clause out of a sentence without effectively changing the meaning of the sentence. Here's an example:

Students who read regularly are prepared for the SAT.

If you remove the clause "who read regularly," the meaning of the sentence would be substantially changed. You'd be left with "Students are prepared for the SAT." Because you can't remove the clause without changing the meaning of the sentence, this clause shouldn't be surrounded by commas.


What's a Non-Restrictive Clause?

A non-restrictive clause isn't essential to the meaning of the sentence. If you got rid of the clause, you'd have less information, but the overall meaning of the sentence would remain the same. Here's an example sentence with the non-restrictive clause underlined.

Joe's parents, who constantly call him, are very overprotective.

The clause "who constantly call him" adds more information about Joe's parents, but if it were removed, the meaning of the sentence would be the same. There would be less information about Joe's parents, but they would still be described as overprotective. This is what the sentence looks like after removing the non-restrictive clause:

Joe's parents are very overprotective.


What Is an Appositive?

An appositive is a descriptive phrase that doesn't include a verb. Similar to a non-restrictive clause, an appositive can be removed without changing the meaning of the sentence. Here's an example with the appositive underlined:

Val, a Wisconsin native, loves fried cheese curds.

If we get rid of the appositive, the sentence still has the same meaning:

Val loves fried cheese curds.



Fried cheese curds are rather delicious.

Kirk K/flickr


SAT Example


In this sentence, "the centerpiece" is an appositive that adds more information about the mural. Because appositives must be surrounded by commas, there should be a comma after "centerpiece." Immediately, we know that A and C are wrong. In answer choice D, the dash can be used like a comma, but you can't separate a clause with a comma and a dash. There would have to be a dash after "mural" for answer choice D to be right. The correct answer is B.


#6: Commas Can't Separate Two Complete Thoughts

A comma splice is when two independent clauses, or complete thoughts, are separated by a comma, and comma splices create a grammatical error known as a run-on sentence. A run-on sentence occurs when two or more independent clauses aren't separated by the correct punctuation. Here's an example of a comma splice:

Ken likes Selena Gomez, she is his favorite singer.

The clauses before and after the comma are complete thoughts that could stand alone as sentences. There are a few ways to correct a comma splice. You can put a conjunction after the comma:

Ken likes Selena Gomez, and she is his favorite singer.

Also, you can put a relative pronoun after the comma:

Ken likes Selena Gomez, who is his favorite singer.

Finally, you can use a semicolon to correctly separate two complete thoughts:

Ken likes Selena Gomez; she is his favorite singer.



Who doesn't like Selena Gomez? (Lunchbox LP/Flickr)


SAT Example


This is an example of a comma splice. The sentence up until "legs" is a complete thought that could stand alone as a sentence, and the rest of the sentence starting with "they" is also a complete thought. Both A and B are comma splices. Answer choice D is wrong because a conjunction is needed to connect "are characterized" and "are covered." The correct answer is C.


Ready to go beyond just reading about the SAT? Then you'll love the free five-day trial for our SAT Complete Prep program. Designed and written by PrepScholar SAT experts, our SAT program customizes to your skill level in over 40 subskills so that you can focus your studying on what will get you the biggest score gains.

Click on the button below to try it out!

Sign Up!


#7: Semicolons Separate Two Complete Thoughts

Semicolons function like periods; they separate two independent clauses. You should be able to replace semicolons with periods. On the SAT, you may find a randomly placed semicolon, or you may need to replace a comma with a semicolon to fix a comma splice. Here are example sentences with semicolons used correctly and incorrectly:

Incorrect: Because Teresa wanted to please her family; she became a doctor.

Correct: Teresa wanted to please her family; she became a doctor.

The second sentence is correct because the clauses on both sides of the semicolon are independent and could stand alone as sentences.


SAT Example


The clause before the semicolon is not a complete thought; therefore, the semicolon is being used incorrectly. Answer choice C unnecessarily adds "and," and answer choice B is wrong because it places a colon after a dependent clause. The correct answer is D.


#8: A Colon Must Come After an Independent Clause

Colons are usually used to introduce lists or explanations. The key rule for colons is that they must come after a complete sentence. If you end the sentence where the colon is placed, the sentence should make sense and be a complete thought.

Incorrect: Meena enjoys multiple genres of music like: alternative, rap, heavy metal, and country.

Correct: Meena enjoys multiple genres of music: alternative, rap, heavy metal, and country.

The first sentence is incorrect because the part of the sentence that comes before the colon isn't a complete thought.


SAT Example


Because the clause before the colon is a complete thought and it's setting up a list, the colon is being used correctly. The types of people listed after the colon are the narrator's colleagues. Because "colleagues" isn't part of the list, you can't substitute the colon for a comma. Also, you can't use a semicolon in place of the colon because there isn't a complete thought after the punctuation. The correct answer is A.



Colons do more than just form an essential part of the happy face emoji.


#9: Use Apostrophes Correctly to Form Possessives

The SAT tests you on how to use apostrophes to correctly form possessives. Luckily, the rules for forming possessives are pretty straightforward. If the word is singular or plural but doesn't end in "s," then you add an "s" after the apostrophe to form a possessive. Here are a couple of examples:

I shall be paying a visit to the men's restroom.

My computer's monitor is rather dirty.

To create a possessive for a plural word that does end in "s," just add an apostrophe after the "s." Check it out:

Juan thinks his parents' rules are too strict.

Also, only use apostrophes for possessives or contractions. Contractions are formed when you combine two words. Examples include it's (it is), don't (do not), and isn't (is not). Don't use apostrophes to create plural nouns.


SAT Example


Because the body is is being discussed in general terms, we should use the singular possessive in this sentence; the sentence is referring to the biological clocks of the body. We can immediately get rid of A because "bodies" is a plural noun; it's not in the possessive form.

Also, answer choice B is wrong because bodies' is the plural possessive form. Additionally, there shouldn't be an apostrophe after the "s" in "clocks." Don't use apostrophes to form plural nouns; only use apostrophes for possessives and contractions. Similarly, answer choice D is wrong because of the apostrophe before the "s" in clocks; the correct answer is C.


#10: Subjects and Verbs Must Agree

Subjects and verbs must agree, meaning that you must use the singular form of a verb with a singular subject and the plural form of a verb with a plural subject. Here's an example:

Incorrect: High school students loves learning grammar rules.

Correct: High school students love learning grammar rules.




If the verb is in the present tense and the subject is in the third person (he/she/it/they), the verb usually ends in "s" in the singular form and doesn't in the plural form. In the example sentence, the subject is "students," which is plural; therefore the verb should be in the plural form.

On the SAT, subject verb agreement questions can be more difficult because there may be a phrase separating the subject from the verb. Check out this example:

Incorrect: The members of the committee meets every Tuesday.

Correct: The members of the committee meet every Tuesday.

The subject of the sentence is "members," which is plural. Therefore, the verb should be in the plural form. The prepositional phrase "of the committee" separates the subject from the verb. If a verb is underlined on the SAT, make sure that you identify the subject that corresponds with that verb to ensure that the subject and verb agree. Also, keep in mind that a subject can never be part of a prepositional phrase.


SAT Example


To determine if there's a subject verb agreement error, we have to identify the subject that corresponds with the verb "portrays." What portrays animals? The works of art do. The phrase in between the commas separates the subject from the verb. The subject is plural because "works" is plural and "of art" is a prepositional phrase. The plural form of "portrays" is "portray," and the correct answer is C. Answer choices B and D are not plural verbs; "portraying" is a gerund that would create a fragment, and "has portrayed" is the singular form of the present perfect tense.


#11: Modifiers Must Be Next to What They're Modifying

The general rule regarding modifiers is that they must be next to what they're modifying. The most common type of modifier error on the SAT is a dangling modifier. When a sentence begins with a modifying phrase, the introductory phrase must be immediately followed by a comma and then the noun the phrase is describing. Here's an example of a dangling modifier:

A determined writer, Jessica's goal is to get her first novel published this year.

The way the sentence is written makes it seem like Jessica's goal is a determined writer. There are a couple of ways to fix the sentence. You can place the noun that is being modified right after the comma:

A determined writer, Jessica has a goal of getting her first novel published this year.

Or you can place the subject in the introductory phrase:

Because Jessica is a determined writer, her goal is to get her first novel published this year.




SAT Example


This sentence makes it seem like the visitor was dotted with pin-sized knobs. Logically, the sentence should indicate that the drawers were dotted with pin-sized knobs. Similarly, answer choices B and C are misplaced modifiers that infer that the there was a visitor dotted with knobs. The correct answer is D.


#12: Pronouns Must Agree With Their Antecedents in Number

This rule means that a plural pronoun must refer to a plural noun and a singular pronoun must refer to a singular noun. Here's an example of a pronoun number agreement error:

Kristin sold their car.

The pronoun "their" is referring to the car of Kristin. Because Kristin is one person and "their" is a plural pronoun, this sentence has a pronoun agreement error. This is the corrected version:

Kristin sold her car.


SAT Example



It's easy to make a careless mistake on this question because you may see the singular pronoun "it" and assumed the underlined pronoun should be singular as well. However, the pronouns have different antecedents. The word "it" refers to 1-MCP, which is singular, and "their" refers to apples, which is plural. The possessive pronoun agrees with the antecedent, and there's no error.

Answer choice A is correct. Answer choice C is a singular possessive pronoun, D is the contraction of "it is," and B is a homophone of the correct answer, but it's the wrong word.


Other SAT Writing Grammar Rules

While the rules I explained are the most often tested on SAT Writing, there are some other grammar rules that will be tested. Here are links to other articles that explain the remaining grammatical rules you need to know for the SAT. These are articles for ACT English, but again, because the two sections are so similar, you can use these articles to prepare:


What's Next?

In addition to the grammar questions on SAT Writing, you need to know how to correctly answer style questions. Learn about add and delete, transitions, and macro logic.

Also, because ACT English and SAT Writing are very similar, make sure to read this article about whether to take the ACT or the SAT.

Finally, as you're preparing for the SAT, learn the pros and cons of different test prep methods.


Want to improve your SAT score by 160 points?

Check out our best-in-class online SAT prep program. We guarantee your money back if you don't improve your SAT score by 160 points or more.

Our program is entirely online, and it customizes what you study to your strengths and weaknesses. If you liked this Writing and grammar lesson, you'll love our program. Along with more detailed lessons, you'll get thousands of practice problems organized by individual skills so you learn most effectively. We'll also give you a step-by-step program to follow so you'll never be confused about what to study next.

Check out our 5-day free trial:

Improve Your SAT Score by 160+ Points, Guaranteed


Have friends who also need help with test prep? Share this article!

author image
Justin Berkman
About the Author

Justin has extensive experience teaching SAT prep and guiding high school students through the college admissions and selection process. He is firmly committed to improving equity in education and helping students to reach their educational goals. Justin received an athletic scholarship for gymnastics at Stanford University and graduated with a BA in American Studies.

Get Free Guides to Boost Your SAT/ACT
100% Privacy. No spam ever.

Student and Parent Forum

Our new student and parent forum, at, allow you to interact with your peers and the PrepScholar staff. See how other students and parents are navigating high school, college, and the college admissions process. Ask questions; get answers.

Join the Conversation

Ask a Question Below

Have any questions about this article or other topics? Ask below and we'll reply!