Grammar Rules You Should Know by Heart Before Taking the ACT: Part I

Grammar Rules You Should Know by Heart

Before Taking the ACT: Part I


I freaking loved the English section of the ACT. I loved the English portion of any standardized test, because it was the section that just made sense to me. Those “Choose the sentence with the correct grammar” questions were my jam. Naturally, when I decided to tackle the must-know grammar rules for this blog post today, I figured it would also be a breeze. Not so much!

It turns out that, while I can identify sentences with correct grammar and sentences with incorrect grammar, I can’t really explain why they’re correct or incorrect. It’s like those math whizzes who can solve a problem in the blink of an eye but couldn’t walk you through how they got to the answer. Just like I relied on my memorized math rules to scrape by, there are a few hard and fast grammar rules you’ll absolutely want to memorize before taking the ACT – especially if English is your weak spot.

Learn and love the following rules, courtesy of PrepScholar, before taking your ACT, and you’ll have a much easier time with the grammar-related questions. And don’t worry – these grammar rules may sound complex at first, but they’re pretty simple when we walk through them together.


“Surround non-restrictive clauses and appositives with commas.”

First, let’s break down what these words actually mean. Non-restrictive clauses are clauses that do not change the meaning of the sentence. They are the opposite of restrictive clauses, which – you guessed it! – do change the meaning of a sentence.

Nonrestrictive clause: My best friend Sloan, who has brown hair, is the nicest person I know.

Restrictive clause: Friends who spend time with me are the nicest people I know.

The first one is non-restrictive because you can take out the entire underlined section and it still makes complete sense (“My best friend Sloan is the nicest person I know.”)

The second one is restrictive because if you take out the underlined clause it makes no sense. (“Friends are the nicest people I know.” All friends? What kinds of friends? I must know more!)

Appositives are clauses that describe a noun and do not have a verb.

Examples: Jeremy, my husband, is a great cook. Kay, my mom, is a wise person. Jack, my dog, loves to eat treats.

All of the clauses underlined add information to the sentence, but they aren’t necessary for the sentence to make sense.

Moral of the story? If you can take an entire clause out of a sentence and the sentence still works, you need to surround that thing with commas!


 “Don’t put a comma before or after a preposition.”

Prepositions are phrases that show the relationship between a noun and another word in the sentence. Prepositions can start with words like above, below, between, during, regarding, upon, via, and with.

Incorrect: The car was parked, below the awning.

Correct: The car was parked below the awning.

Incorrect: I’m going to go shopping, with my sister.

Correct: I’m going to go shopping with my sister.


 “Don’t separate two independent clauses with a comma.”

This mistake is called a comma splice, and it’s a big no-no. Luckily, it’s super easy to identify and fix these mistakes. Independent clauses are clauses that can stand alone as complete sentences. There should never be two back-to-back, separated by a comma.

Incorrect: My neighbor’s house is beautiful, it’s painted yellow.

This homework assignment is really hard, it is going to take me hours.

You can fix these sentences in a few ways. I typically just add a conjunction in the middle, like but or and. You could add a semicolon, but that seems like the more complicated option.

Correct: My neighbor’s house is beautiful, and it’s painted yellow.

This homework assignment is really hard; it is going to take me hours.


 “Use the fewest words possible.”

This is an important rule to remember for the ACT, but please, please remember this rule for life! I edit so many insanely wordy college essays, with rambling sentences that are downright confusing to follow. Remember, sentences aren’t better because they’re longer. It doesn’t make them more impressive – in fact, it does the opposite.

Incorrect: The reason that chemistry is my favorite course is due to the fact that it allows me to engage in many experiments that enable me to discover new things.

Correct: Chemistry is my favorite course, because I enjoy doing experiments and discovering new things.

My favorite college English professor told us to “put our sentences on a diet,” and I swear it changed my life.


 “Modifiers must be next to what they’re modifying.”

Modifiers, or words or phrases that describe a noun, need to be directly next to the thing it’s describing, otherwise things get confusing quickly. Here’s an example of a confusing sentence with a misplaced modifier.

Incorrect: We used the chalkboard hanging in the back of the classroom that was green. The chalkboard is green, but this sentence makes it seem like the classroom is green.

Correct: We used the green chalkboard, which was hanging in the back of the classroom.

Another common mistake is known as dangling modifiers. I’ve seen it explained in a variety of different ways that make it seem more confusing than it actually is, so I’ll try to be straightforward.

Incorrect: After finishing my first day of class, the school year was off to a great start.

“After finishing my first day of class” is a modifier, and it should immediately be followed by whatever it is modifying. “The school year” didn’t just finish “my first day of class,” so the modifier is just dangling there.

Correct: After finishing my first day of class, I was excited for the rest of the school year.


 “Keep verb tenses consistent.”

This is pretty simple: all verbs in a sentence should be in the same tense. You shouldn’t have one verb in present tense immediately followed by another verb in past tense.

Incorrect: I studied in the library all day long and I go to the coffee shop at night

Correct: I study in the library all day long and I go to the coffee shop at night.

OR: I studied in the library all day long and I went to the coffee shop at night.


 “Choose the right word based on context.”

Some questions will ask you to pick the right word for an underlined section, and those can be tricky if you don’t know the exact meanings of your options. If you don’t know what a specific word means, read and re-read the sentence to understand the context. Then, use process of elimination to narrow down your options and make an educated guess.

Sometimes you’ll need to choose between homophones, like their, they’re, and there, your and you’re, and who’s and whose. My recommendation is to LEARN YOUR CONTRACTIONS. If there is an apostrophe, it is two words smushed together. I don’t really have a fancy or proper trick to teach you this… I’d recommend making flashcards if you struggle with these.

Once you’ve read over these rules and looked at the examples, I’d recommend going online and doing practice questions. You can find practice questions here. Next week, I’ll be bringing you seven more grammar rules to know before taking the ACT