The 13 ACT and SAT Grammar Rules You Need to Know

Bonus Material: PrepMaven’s ACT and SAT Grammar Workbook ( 100+ Practice Questions )  

Both the ACT and the SAT are interested in your ability to apply certain English grammar rules.

The good news, however, is that these exams only test 13 foundational rules. 

In this post, you’ll find these 13 grammar rules tested regularly on ACT English and SAT Writing & Language. We explain these rules as simply as possible, and without grammar jargon.

Plus, we include links to other detailed posts that elaborate on individual concepts, provide strategies for approaching certain questions, and walk you through guided examples from official practice tests.

You’ll also be able to download free practice worksheets for every single grammar rule, which include practice questions, additional guided examples, and answers and explanations.

If you want all of these worksheets in one place, simply grab our ACT and SAT Grammar Workbook below.

Here’s what we cover in this post:


ACT and SAT Grammar in a Nutshell

First things first: let’s talk about what you can expect from the ACT and the SAT in terms of grammar questions.

Where Will I See Grammar Questions on the ACT/SAT?

Students can expect to directly apply their knowledge of English grammar on the following 2 sections:

  • ACT English
  • SAT Writing & Language

ACT English is the first section of the ACT exam and contains 75 questions to be completed in 45 minutes. SAT Writing & Language is the second section of the SAT test and contains 44 questions to be completed in 35 minutes.

As we mention in the introduction to this guide, proficiency in English grammar can also be helpful on the essay portion of either test, as essay graders assess writers’ application of English conventions when scoring.

How Many Grammar Questions Will I Encounter?

Not all questions on ACT English and SAT Writing & Language concern grammar.

Both tests include questions that we like to call Expression of Ideas questions, which test students’ understanding of context, vocabulary, logical connection of ideas, and the expression of an author’s purpose.

These can take a little more time than basic grammar questions and can be more challenging.

We’ve analyzed officially released ACT and SAT practice tests to come up with an approximation of how many rote grammar questions you’ll see on each test.

Grammar Questions on the ACT Grammar Questions on the SAT
~36-40 (out of 75 total questions) ~18-22 (out of 44 total questions)

Notice how grammar questions account for approximately 50% of the questions on both ACT English and SAT Writing & Language (give or take a few percentage points).

What does this mean? Students need more than proficiency in English grammar to earn a competitive score on both sections.

How Will I Know If It’s a Grammar Question?

One of the most important things SAT and ACT test-takers can do on any section of the test is to identify the type of question in front of them. This can be vital for applying strategies and sidestepping typical SAT and ACT tricks.

On ACT English and SAT Writing & Language, you know you’re navigating a grammar question if you see any of the following changing in the answer choices:

  • Punctuation (including type and placement)
  • Verb tense and form
  • Pronouns
  • Prepositions
  • Idiomatic phrases and words

For example, take a look at the following sample question taken from an officially released ACT practice test (#1). Most especially, try to identify what differs between the answer choices.

Verbs on the SAT and ACT_Sample Question The fact that the form of the verb build changes in the answers indicates that this is a Grammar question. Verbs are a commonly tested English grammar concept on both tests.

On the other hand, take a look at what is different about this question, taken from an officially released SAT practice test (#1):

Expression of Ideas question_SAT Writing & Language Did you notice that this has a full question in front of it? And that this question is asking students to consider the choice that provides the most relevant detail?

The differences in the answer choices don’t boil down to mere grammar rules. They boil down to ideas, and a student’s capacity to figure out which is “relevant” in context, given the author’s ideas. This is an Expression of Ideas question.

Note: even though the CollegeBoard describes the SAT Writing & Language section as a test that assesses your ability to fix mistakes, plenty of grammar questions are correct as written! The same goes for ACT English. That “NO CHANGE” option is just as viable an answer choice as all the others.

We discuss the 13 ACT and SAT grammar rules you’ll need to know to succeed on ACT English and SAT Writing & Language next.


The 13 ACT and SAT Grammar Rules You Need to Know

As we mentioned earlier, students don’t need to memorize every single English grammar rule to feel confident on ACT English or SAT Writing & Language.

These tests are only interested in a finite list of grammar concepts. What’s more, these grammar concepts are tested in very predictable, limited ways.

That’s why we won’t elaborate everything there is to know about Verbs, for example, or the nuanced difference between a colon and a semicolon in this guide. While interesting and useful, such details aren’t necessarily relevant for the purposes of the ACT and SAT.

The rules as we present them here are simplified and efficient, designed to give you the information you need to know to answer an ACT or SAT grammar question correctly. We discuss each concept in-depth in individual blog posts, linked throughout.

Complete Guide to ACT and SAT Grammar Rules_PrepMaven (1)

So, without further ado, let’s get started. We begin with the most heavily tested grammar concepts and work our way down from there.


ACT and SAT Grammar Rules: Punctuation

Punctuation is by far the most common English grammar concept that appears on both the ACT and the SAT.

Based on our analysis of officially released ACT and SAT practice tests, we’ve crafted a breakdown of the number of punctuation questions students can expect on either test:

Punctuation Questions on the ACT Punctuation Questions on the SAT
12-16 5-7

Most punctuation questions on SAT Writing & Language and ACT English actually test something more foundational than your knowledge of punctuation rules: your capacity to correctly identify incomplete and complete sentences. We’ve written an entire post on this–that’s how important this skill is for SAT and ACT test-takers!

You can also download this free worksheet for additional practice in identifying incomplete/complete sentences. We’ll reference complete and incomplete ideas often in the following 7 punctuation rules.

For now, here’s a general breakdown of the difference between the 2 sentences:

Complete Sentences Incomplete Sentences

Have:

  • subject
  • verb
  • full expression of an idea

Don’t have:

  • subject
  • verb
  • and/or full expression of an idea

Your knowledge of this difference will be vital for the majority of the following rules. Let’s dive into those 7 punctuation rules you need to know for the SAT and ACT now.

Rule #1: You can only join 2 complete sentences with a period, a semicolon, or a comma + FANBOYS conjunction.

Let’s say that you’ve identified two complete sentences in an ACT or SAT punctuation question, as in this example here:

It’s not that people are disinterested

in climate 12 change, many would

argue that citizens are very interested in

the planet’s gradual warming.

A) NO CHANGE

B) change; many

C) change many

D) change

“It’s not that people are disinterested in climate change” is a complete sentence (it has a subject, a verb, and the full expression of an idea); the same goes for “many would argue that citizens are very interested in the planet’s gradual warming,” for the same reasons.

At this point, it’s time to choose the punctuation that is appropriate for combining 2 complete sentences: a semicolon, period, or a comma + FANBOYS conjunction (for, and, nor, but, or, yet, so).

On the SAT or ACT, you will never have to choose between one of these three options (i.e., a semicolon versus a period). In fact, if you see a semicolon and a period in the answer choices–and nothing else differs between those options–you can automatically cross those choices off, as you can’t have two right answers.

In the example above, the only permissible answer choice is B, which uses a semicolon to join 2 complete ideas. With this choice, this is how the new sentence would read:

It’s not that people are disinterested in climate change; many would argue that citizens are very interested in the planet’s gradual warming.

You could also write this sentence using a period or a comma + FANBOYS conjunction, as in these two examples:

It’s not that people are disinterested in climate change. Many would argue that citizens are very interested in the planet’s gradual warming.

It’s not that people are disinterested in climate change, for many would argue that citizens are very interested in the planet’s gradual warming.

Rule #2: Use a single comma to join 1 complete sentence with 1 incomplete sentence.

There is only one option for combining a complete sentence and incomplete sentence: a single comma.

Now, if the incomplete sentence is in fact just a phrase (as opposed to a clause, which has a subject and a verb), this could mean we’re in the territory of either comma rules or colon rules, which we discuss later on in this post. For example, if your incomplete sentence is a transition phrase, like “on the other hand,” chances are, it’s time to apply some comma rules! 

The following example asks us to combine an incomplete sentence with a complete one:

In light of the fact that women are still

earning less than men in the workplace, 

31 for example: equity consulting

companies are likely to prove their value in

years to come.

A) NO CHANGE

B) for example; equity

C) for example, equity

D) for example. Equity

“In light of the fact that women are still earning less than men in the workplace, for example” is an incomplete sentence.“Equity consulting companies are likely to prove their value in years to come” is a complete sentence.

We can only use a single comma to join 1 incomplete sentence to 1 complete sentence. The only answer choice that has a single comma as a solution is C.

The corrected sentence would thus read as follows:

In light of the fact that women are still earning less than men in the workplace, for example, equity consulting companies are likely to prove their value in years to come.

For more practice with combining sentences on the SAT or ACT, check out our Combining Sentences blog post or download this free Combining Sentences worksheet for practice questions, guided examples, and more. 

Rule #3: Use 2 commas or 2 long dashes to separate non-essential, additional information from the rest of a sentence.

Just as we use parentheses to separate additional information from the rest of a sentence, we can use 2 commas or 2 long dashes to accomplish the same goal.

What is “additional” or “non-essential” information?

This includes anything that is not essential for making a sentence complete (i.e., a subject, verb, or words that contribute to the full expression of an idea), such as descriptive phrases and transition words. Essentially, if you get rid of this information, you’ll still have a complete sentence.

Take a look at this example:

Greg and Kevin, the co-founders of PrepMaven, emphasize the importance of character when it comes to college applications.

Can you spot the non-essential information in this sentence? If you guessed “the co-founders of PrepMaven,” you’re absolutely right!

“The co-founders of PrepMaven” is a descriptive phrase that provides more information about the sentence’s subject, “Greg and Kevin.” It is not needed to make the sentence complete. In fact, we could get rid of it and still have a complete sentence!

Greg and Kevin emphasize the importance of character when it comes to college applications.

That’s why we can separate “the co-founders of PrepMaven” with either 2 commas or 2 long dashes:

Greg and Kevin, the co-founders of PrepMaven, emphasize the importance of character when it comes to college applications.

Greg and Kevin–the co-founders of PrepMaven–emphasize the importance of character when it comes to college applications.

Rule #4: Place a comma after a transition word or introductory phrase.

A “phrase” is simply a group of words. Phrases are different from clauses, which contain a subject-verb pair (and can be complete or incomplete). An introductory phrase begins a sentence, often providing context, time or location cues, or transitions, as in the following examples:

In 1938

On the other hand

Beneath the sofa 

If you start a sentence with an introductory phrase or transition word, you need to place a comma after it. That’s all there is to it!

In 1938, historians were only just starting to comprehend the impact of the changing times.

On the other hand, such precautionary measures are ones we should be taking on a daily basis, not merely in times of crisis.

Beneath the sofa, Lucy found a panoply of forgotten items, including a keyring, dog toy, and grocery receipt.

Rule #5: Separate items in a list with commas.

This tends to be the simplest comma rule for students to remember. 

When listing out items, use a comma to separate each item. On the SAT and ACT, you’ll also need a comma before the and that finishes the list, as in this example here:

Before I leave for the holidays, I need to find a babysitter, submit that annual report, and RSVP for the Christmas party.

In this example sentence, the “items in a list” are actually phrases: find a babysitter, submit that annual report, and RSVP for the Christmas party. We use commas to separate them, including before the “and.” 

For more practice with comma rules on the SAT or ACT, check out our Comma Rules blog post or download this free Comma Rules worksheet for practice questions, guided examples, and more. 

Rule #6: A complete sentence must precede a single long dash or colon.

When it comes to using a colon or single long dash properly, it’s particularly important to know what makes up a complete sentence.

That’s because of this one important rule: the sentence that precedes a colon or single long dash must be complete.

It doesn’t matter what comes after a colon or single long dash, really–incomplete sentence, complete sentence, a phrase, a single word. All that matters is that the sentence that comes before the colon or single long dash is complete. That’s it!

Here’s an example sentence, written with a colon and a single long dash respectively, that shows this rule in action:

Eighteenth-century female painters were, to no one’s surprise, forbidden from painting many “scandalous subjects:” chief among these subjects was the male figure.

Eighteenth-century female painters were, to no one’s surprise, forbidden from painting many “scandalous subjects”–chief among these subjects was the male figure.

“Eighteen-century female painters were, to no one’s surprise, forbidden from painting many “scandalous objects”” is a complete sentence. Remember: it doesn’t matter what comes after the colon or single long dash, as long as that first sentence is complete.

You will never have to choose between a semicolon, period, colon, or single long dash if all are used correctly.

For more practice with colon and long dashes on the SAT or ACT, check out our Colons and Long Dashes blog post or download this free Colons and Long Dashes worksheet for practice questions, guided examples, and more. 

Rule #7: Use apostrophes to show possession with plural and/or singular nouns, and be careful with contractions.

We use apostrophes to show possession and contraction. When it comes to possession rules, keep the following in mind:

  • Add an ‘s to singular nouns showing ownership
  • Add a single apostrophe to plural nouns showing ownership

Check out these examples of singular noun possession:

  • Dmitri’s dreams
  • The cat’s favorite window sill
  • The Earth’s curvature

How can you tell if a noun is singular? There should be only one of that particular noun. For example, there is only one Dmitri, one cat, and one Earth in the sample phrases above.

Here are some examples of plural noun possession:

  • The books’ covers
  • The sidewalks’ cracks
  • My teachers’ curriculum

Besides the fact that these plural nouns end in “s,” you can tell that they are plural because there is more than one of each. From the examples, we know that we are discussing more than one book, sidewalk, and teacher.

What about singular nouns that end in “s,” including proper nouns like Chris? You still follow the rule of adding an ‘s to these nouns. Here’s what that would look like:

  • Chris’s classes
  • The iris’s stamens
  • The sea bass’s flavor

We know it feels awkward, but that’s the rule! The only exception to this is with proper nouns that have historical and/or biblical associations, like “Moses” or “Jesus.” In these instances, all you need to do is add an apostrophe to the end:

  • Moses’ leadership
  • Jesus’ teachings

You can have a plural noun that doesn’t end in “s”. What happens if you want to show possession with one of these nouns? All you need to do is treat it like a singular noun: add an ‘s to the end. Check out these examples:

  • The children’s games
  • People’s voting habits
  • Women’s rights

Finally, although contractions appear relatively infrequently on ACT English and SAT Writing & Language, it’s important to know the difference between the following pronouns and similar contractions:

  • its vs. it’s
  • their vs. they’re
  • your vs. you’re
  • whose vs. who’s
For more practice with apostrophe rules on the SAT or ACT, check out our Apostrophes blog post or download this free Apostrophes worksheet for practice questions, guided examples, and more. 

ACT and SAT Grammar Rules: Verbs

Verbs are the second most prominent English grammar concept on the ACT and SAT. It always surprises students when they find out that they will only have to apply 2 verbs rules to the SAT and ACT. Verbs are essential components of the English language, and we use them all the time!

However, ACT English and SAT Writing & Language are only interested in your knowledge of two things:

  1. Verb tense
  2. Subject-verb agreement

That’s all! In general, students can expect to encounter the following number of Verbs questions per test:

Verbs Questions on the ACT Verbs Questions on the SAT
5-11 2-6

Let’s dive into the 2 verbs usage rules you need to know now.

Rule #1: Verb tense must remain consistent

Verb tense refers to the ‘time zone’ of a verb, indicating when this action, occurrence, or state of being is happening.

In general, the tense of the verb in question must match the tense of the surrounding context.

The surrounding context might mean the sentence itself. It could also mean a part of a sentence or the paragraph as a whole. This is why it is so important to read carefully for context when encountering any Verbs question on ACT English or SAT Writing & Language!

So, if a sentence begins with the phrase “In 1989,” we can assume that the tense of that sentence will be in the past, given that 1989 is a year that has already occurred. If a paragraph is discussing an ongoing condition, such as “modern businesses’ efforts to maximize workplace efficiency,” we can assume that the tense of this paragraph will be, for the most part, in the present.

The key is to mine your context for clues that indicate what the tense standard is, and then ensure that your answer choice matches that tense. Here are some examples of common verb tense “clues” on ACT English and SAT Writing & Language:

  • Another verb in that tense in context (i.e., “studied,” “will walk,” or “breathes”)
  • A time clue (i.e., “In 1989,” “last year,” or “in the coming decade”)
  • A transition word or phrase (i.e., “meanwhile,” “lastly,” or “at first”)

Rule #2: Verbs must match their subjects

This is the heart of subject-verb agreement: verbs must match their subjects!

But what do we mean by “match”? Verbs must match their subjects in form, which is different from tense.

Here’s what that generally breaks down to:

  • A plural noun must have a plural verb
  • A singular noun must have a singular verb

A plural noun is a noun that indicates more than one of some thing, idea, or individual: horses, children, mosses. A singular noun indicates that there is only one of some thing, idea, or individual: horse, child, moss.

Now, even though we don’t always think of verbs in terms of their singularity or plurality, a verb will change form depending on whether its noun is plural or singular. Take a look at the following examples to see this in action:

  • The horses run across the field.
  • The horse runs across the field.
  • These mosses are hard to identify.
  • This moss is hard to identify.

In the first two examples, the plural noun (horses) matches the plural verb (run), while the singular noun (horse) matches the singular verb (runs). Run and runs are different verb forms.

In the second two examples, the plural noun (mosses) matches the plural verb (are), while the singular noun (moss) matches the singular verb (is). Are and is are different verb forms.

Now, our ears are pretty good at “hearing” when subject-verb agreement is off. Notice, for example, how “wrong” these phrases sound when you read them out loud or in your head:

  • Horses runs across the field.
  • The moss stick to the tree.
  • Mary deliver the book to her friend.
  • Cross-contamination are common.

These all sound “wrong” to our ears because the agreement is incorrect. You can apply the same test to verb and subject combinations on the ACT or SAT, and eliminate those that clearly don’t sound “right.”

Note: The SAT and ACT both love to cram in a bunch of words between a subject and its verb to confuse students. That’s why it’s so essential to practice identifying a sentence’s subject and its associated verb correctly, which we discuss in our Verbs blog post and worksheet.

For more practice with verbs on the SAT or ACT, check out our Verbs blog post or download this free Verbs worksheet for practice questions, guided examples, and more. 

ACT and SAT Grammar Rules: Pronouns

A pronoun is a word that takes the place of a noun. We use pronouns so that we don’t have to say the same noun over and over again in a sentence or paragraph. That’s what makes them so useful!

Of course, there are several different types of pronouns, and for the purposes of ACT and SAT grammar, it will be important to know the basic difference between the most common types, outlined in the chart below.

Subject Pronoun Object Pronoun Possessive Adjective Possessive Pronoun Reflexive Pronoun
I me my mine myself
you you your yours yourself / yourselves
we us our ours ourselves
they them their theirs themselves
she her her hers herself
he him his his himself
it it its n/a itself

Pronoun questions do not appear as frequently as, say, punctuation questions on ACT English or SAT Writing & Language. Take a look at the following estimate of Pronoun questions that appear on each test, based on our analysis of officially released practice tests:

Pronoun Questions on the ACT Pronoun Questions on the SAT
2-5 1-5

Yet knowledge of pronouns is still vital! Luckily, for the purposes of the ACT and SAT, pronoun usage essentially boils down to just one rule, which we discuss below.

Rule #1: A pronoun must match its noun and stay consistent in context.

This might sound fairly obvious, but it holds a lot of meaning on ACT English and SAT Writing & Language. 

A pronoun must match its noun in both type and form. For example, an object pronoun (me, you, us, them, her, him, it) must replace a noun that functions as a direct object. The same goes for subject pronouns, possessive adjectives, possessive pronouns, and reflexive pronouns.

Here’s a list of pronouns and their nouns (called antecedents) that demonstrate this correlation:

  • people’s voices –> their voices
  • Give the gift to Roger  –> Give the gift to him
  • I don’t know anything about trigonometry –> I don’t know anything about it
  • Ms. Lutz is teaching the class –> she is teaching the class
  • This book is Susan’s –> This book is yours

All of the pronouns in these examples match their nouns (antecedents) in type and form. We wouldn’t replace, for example, “people’s” with “hers” or “trigonometry” with “them.”

One of the most common pronoun mistakes confuses object pronouns for subject pronouns, as in the following incorrect sentences:

  • Her and I plan on traveling to Uruguay soon.
  • Mr. Banks, whom is teaching the class, has a wide range of advanced degrees.

In these sentences, the writer is erroneously using an object pronoun in place of a subject pronoun. If you ever are unsure about the difference, simply replace the pronoun with a noun to test it out:

  • Kate and I plan on traveling to Uruguay soon –> Kate = “she” –> She and I plan on traveling to Uruguay soon.
  • Mr. Banks is teaching the class. –> Mr. Banks = “who” –> Mr. Banks, who is teaching the class, has a wide range of advanced degrees.

We talk further about the difference between subject and object pronouns, especially who vs. whom, in our Pronouns blog post.

What do we mean by a pronoun staying “consistent”? In general, if you start out with one pronoun in a sentence, you have to stick with it. This is especially important when using the pronouns you and one.

For example, this is an example of pronoun inconsistency (which would be incorrect on the SAT or ACT):

If you keep walking for about five blocks, one will spy a curious sight.

Both “you” and “one” in this sentence technically refer to the same general individual, but we need to use one or the other (not both). Here is a correct version of this sentence that shows pronoun consistency:

If you keep walking for about five blocks, you will spy a curious sight.

One More Pronouns Tip

ACT English and SAT Writing & Language love testing students’ knowledge of the difference between contractions and possessive pronouns. Make sure you know these differences!

Here are some commonly confused contractions and possessive pronouns:

  • they’re vs. their vs. there
  • its vs. it’s
  • whose vs. who’s
  • your vs. you’re
For more practice with pronouns on the SAT or ACT, check out our Pronouns blog post or download this free Pronouns worksheet for practice questions, guided examples, and more. 

3 Rarely Tested ACT and SAT Grammar Rules

We do see some miscellaneous grammar topics tested on ACT English and SAT Writing & Language. While these are rarely tested, sometimes appearing in just one question per exam, they are still worth reviewing.

These topics come down to just 3 grammar rules, outlined below.

Rule #1: Modifiers must be placed correctly.

A “modifier” refers to a word or group of words that provide more information about a certain subject. In most Modifier questions on the SAT or ACT, a modifier is a descriptive phrase that provides additional details about a subject, often appearing at the start of a sentence.

Here are some examples of modifying phrases that might offer further details about a specific subject:

walking down the street

bespectacled and grimacing

associated with ancient tradition

In general, modifiers and modifying phrases must be right next to whatever it is they are modifying! Take a look at these sample sentences that use the modifying phrases above:

Walking down the street, my friend and I took in the gorgeous sunset.

Bespectacled and grimacing, the professor made his way to the lectern.

Associated with ancient tradition, the practice of ancestral worship appears in many cultures.

In all of these examples, the modifying phrases are placed directly next to the subject they are modifying. Misplaced modifiers are called “dangling modifiers,” and these incorrectly modify a subject. Here are the same examples written with dangling modifiers:

My friend and I took in the gorgeous sunset, walking down the street. 

The professor made his way to the lectern, bespectacled and grimacing.

The practice of ancestral worship appears in many cultures, associated with ancient tradition.

Technically, due to the misplacement of modifiers, these sentences declare that it is the sunset that is “walking down the street,” the lectern that is “bespectacled and grimacing,” and the cultures that are “associated with ancient tradition.” In reality, the friends are walking down the street, the professor is bespectacled and grimacing, and the practice of ancestral worship is associated with ancient tradition.

Modifiers appear every so often on ACT English and SAT Writing & Language, and generally with higher frequency on the ACT. 

Rule #2: Utilize the appropriate idiom, when applicable.

An “idiom” is a fixed component of a language. Idioms are often hard to translate into other languages, like the English phrase it’s raining cats and dogs. It can be equally difficult to learn an idiom in another language–most language learners must simply memorize these turns of phrase.

Idioms do appear on ACT English and SAT Writing & Language, but in very specific ways. Yes, these questions are often easier for native English speakers, but that doesn’t mean they aren’t fair game for all test-takers, regardless of English proficiency.

That’s because Idiom questions on the ACT and SAT generally have to do with the following:

  • prepositional phrases
  • homonyms

Prepositions help show relationships between places, things, people, ideas, time, and more. Here’s a list of the most commonly used prepositions in the English language.

on

at

with

of

before

without

in

to

at

by

into

toward

behind

against

for

as

from

about

around

after

Small, functional words, prepositions are easy to overlook. However, many prepositions are idiomatic, especially when associated with certain adjectives and verbs. Take a look at these phrases, for example, that must be connected with one specific preposition.

  • accustomed to
  • protest against
  • associated with
  • curious about 
  • necessary for
  • at last
  • in general
  • as a means of
  • by all means
  • from time to time

These are all fixed idiomatic phrases. We wouldn’t say, for example, “associated on” or “curious into.” Much like subject-verb agreement, our ears can often tell when an idiomatic phrase is incorrect, but it’s also vital to ensure your familiarity with some of these commonly tested idioms as they can be easy to breeze by!

The SAT and ACT are also interested in your capacity to distinguish between certain homonyms, words that sound the same but have key differences in meaning. Here are some very common homonyms that have appeared on official SAT and ACT tests. Notice how some of these have already appeared in our discussion of apostrophes and pronouns:

  • affect vs. effect
  • than vs. then
  • fair vs. fare
  • whose vs. who’s
  • its vs. it’s
  • their / there / they’re
  • your vs. you’re

Rule #3: Apply parallel structure for comparisons or items in a list.

Parallelism isn’t just a concept that appears in math. It also concerns grammatical structure, especially with respect to comparisons or lists.

To apply parallel structure, ensure that items in a comparison or list are in the same form, category, and/or number.

In this next example, the verbs in the list all have the same form (-ing):

Desmond spends his days at the library photocopying, transcribing, and cataloguing articles.

Here, the nouns in the list are all singular, reflecting parallelism in number:

Someday I hope to invest in a car, a retirement account, and a rental property.

Lastly, in this comparison, notice how the sentence compares nouns that are the same “category:” i.e., the “car enthusiasts of this show” and “those” of “past events.” This is parallel structure, too, as it’s technically grammatically incorrect to compare things that do not follow the same cateogry.

The car enthusiasts at this road show, however, seemed far less interested than those of past events.

For more practice with these 3 miscellaneous grammar rules on the SAT or ACT, check out our 3 Rarely Tested Grammar Rules on the SAT and ACT blog post or download this free Rarely Tested Grammar Rules on the SAT and ACT worksheet for practice questions, guided examples, and more. 

Now You Know These 13 ACT and SAT Grammar Rules…What Next?

We’ve covered the 13 ACT and SAT grammar rules you need to know to succeed on ACT English and SAT Writing & Language. What happens now?

We strongly encourage students to spend time working through our individual blog posts for each grammar concept discussed here, as these delve even deeper into the nuances of these rules, especially as they appear on the SAT/ACT:

Students can also download free worksheets for these topics, which include guided examples of official test questions, practice questions, explanations, and more. Find download links in this post.

Otherwise, grab a copy of our ACT and SAT Grammar Workbook that includes all of these worksheets in one single PDF.

SAT and ACT Grammar Workbook

With this workbook, you’ll be able to:

    • Keep these 13 grammar rules all in one place
    • Work through additional guided examples for each question type
    • Practice 10+ questions per grammar concept (that’s 100+ total questions, all free!)
    • Check your performance with detailed answers and explanations


Kate_Princeton Tutoring_AuthorBio Kate M.

Kate is a graduate of Princeton University (B.A. in English Literature and Interdisciplinary Humanities) and Boston University (M.F.A in Creative Writing). Over the last decade, Kate has successfully mentored hundreds of students in all aspects of the college admissions process, including the SAT, ACT, and college application essay.