How do I use Punctuation on the ACT and SAT Exams? Part II

Posted by Colleen on 8/25/17 4:36 PM


College entrance tests require that you know the rules of punctuation. There’s no way around it, so let’s get right to it.

How should I think about punctuation?It just seems like a series of unnecessary marks with complicated rules.

Punctuation is crucial for communication. Punctuations marks act like sign posts that guide a reader through a sentence. A reader might understand every word in a sentence, but he or she needs punctuation to determine how these words fit together.

We have all seen funny punctuation mistakes. Let’s say I want to tell my grandmother that it is time to eat, but I neglect my punctuation skills. So I shout,

“Let’s eat Grandma!”

Oh no—poor Grandma! The lack of a comma could lead to disastrous consequences.

Suggesting that your family eat Grandma is no fun. It is also no fun to take the SAT or ACT and not know the differences among various types of punctuation. Below is a list of the six types of punctuation marks you are most likely to encounter in the exam. 


Periods end sentences. Period.

I am relieved that punctuation rules finally make sense to me.


Semicolons can connect two main sentences.

I love dancing; I practice it every day.

Be careful: the parts before and after the semicolon both need their own subject and verb.

I love dancing and practice it every day.

This sentence could not take a semicolon in place of the “and” since there is no subject for the second half. “Practice it every day” relies on the “I” subject and therefore cannot be separated from it. 


Commas serve a variety of functions. If you need to make a break in a sentence but not end it, you most likely need a comma. Commas come up in the following situations:

  • Items in a series

If there are three or more items in a list, we need commas between them, including before the “and.”

Last summer, I visited Alaska, British Columbia, and Washington.

  • Between two or more adjectives when the order of the adjectives does not matter

the energetic, carefree puppy OR the carefree, energetic puppy

If adjectives cannot be switched, there is no comma between them

ancient Roman art

  • Around parts of the sentence that can be taken out without significantly changing the sentence’s meaning, usually when there is an appositive or aside

Toledo, a city first settled centuries ago, boasts examples of many historical architectural styles.

The sentence retains its meaning if we read it: Toledo boats examples of many historical architectural styles. 

If the aside comes at the end of the sentence, we only have room to put a comma at the beginning, since the period comes at the end.

One place that boasts examples of many historical architectural styles is Toledo, a city first settled centuries ago.

Some words need special attention as to whether or not they introduce material that can be safely removed from the sentence. The words who, whom, whose, which, when, where, and why are especially tricky. Sometimes, they begin descriptions that can be taken out. Other times, they introduce descriptions that are necessary for understanding the sentence.

Rose had never loved the man who was now in her state room.

This sentence needs more context to determine whether the clause “who was now in her state room” is necessary for knowing what man the sentence refers to. 

Rose looked at Cal. Rose had never loved the man, who was now in her state room.

Here, it is clear that “the man” refers to Cal. Therefore, the information in the second sentence further explaining the man’s location is not necessary.

Rose thought about Cal, enjoying his lavish life in first class, and Jack, hidden somewhere in the steerage rooms below deck. Rose had never loved the man who was now in her state room.

In this case, the information about the man is crucial. If we stopped after Rose had never loved the man, we would have no idea which man. Does Rose love Cal or Jack? If we put a comma, we would imply that it does not matter!

This example shows why it is so important to read more than the underlined portion. The sign posts that you include for punctuation show more than just the way through a sentence. They show how all of the parts within the whole passage work together.

  • After an introductory phrase or clause

After I went to the park, I had to go back to studying for the SAT.

On Friday nights, I take a practice ACT test.

If these phrases or clauses had come at the end of the sentence, then we would not use a comma:

I had to go back to studying for the SAT after I went to the park.

I take a practice ACT test on Friday nights. 

This rule is why we do not need commas before words like “because” or “that.” Yes, they are dependent clauses but since they are not at the beginning of the sentence, they do not need commas:

I finally got the grade that I wanted to get.

I never take the highway because I never have any change to pay the tolls.


Colons act as two types of sign posts. Some colons indicate that there is a list coming.

I took three items with me: my passport, my wallet, and my airplane ticket.

When a sentence is leading up to a conclusion, colons also come before the resolution of the idea. 

Once the dementor left, Professor Lupin knew only one thing would calm down the students: chocolate. 


Dashes are a strong piece of punctuation. Think about the word: when you dash off somewhere, you’re really making quite an effort. Even the way dashes look—forming a line piercing the sentence—indicate that they are acting as a sign post for something that we need to sit up and pay attention to.

If you have a single dash, it acts like a strong colon.

The clues all pointed in one direction—guilt.

If you have a pair of dashes, they work like a strong pair of commas.

The masonry—buried for centuries—crumbled when it was exposed to light.


Apostrophes often indicate possession.

That is my sister’s car.

Those are my sisters’ cars.

Those are the women’s cars. 

Apostrophes can also indicate a contraction.

Don’t go!

Pro tip! The words it’s and its can cause confusion. “It’s” is the contraction of “it is.” “Its” is possessive.

Looking for more?

Cambridge Coaching has all of your ACT and SAT test prep covered. Get in touch to see about ways to master the exams and improve your results.

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Want to read additional on SAT and ACT preparation?  Check out these prevoius blog posts:

What's the Difference Between the Old SAT and New SAT? 5 Major Changes on the Reading Section

Reading or Math? How to Decode Word Problems on the New SAT

The Most Common Prefixes and Their Meanings

Tags: ACT, SAT