The 4 Rules for Comma Usage on the ACT® Test

The 4 Comma Rules

The 4 Comma Rules are:

• Punctuation (FANBOYS)
• Oxford Comma
• Extra Info
• Modifiers

Comma FANBOYS

This is the same rule as comma FANBOYS. FANBOYS stands for For, And, Nor, But, Or, Yet, So - the coordinating conjunctions. You can use a comma with a FANBOYS as long as you have a complete sentence on both sides For more info see the punctuation section.

Oxford Comma

The Oxford comma (also called serial comma) is used for three or more items in a list. If you have that, you can use an Oxford comma. There are times when you may or may not use the last comma for the list (sometimes itself called the Oxford comma). You must use the Oxford comma on the ACT® . For example: 'I love apples, bananas, and oranges.' That last comma before 'and' is the Oxford comma.

Example:

There are times when leaving out the Oxford comma can have serious or hilarious ramifications to the meaning of a sentence. Fortunately for us, we will always write clearly what we mean because we're using the Oxford comma on the ACT® .

If you want an example of a time when the Oxford comma cost a company 2 million dollars (and one of the only times ever a grammar teacher got to say, "see! I told you this was important"), follow this link to learn about the lawsuit from a NYTimes article. I find that giving this context helps some students remember the Oxford Comma rule. If that's not you, then skip the link and keep going.

Modifiers

This is a big one on the ACT® English section. It's also a two-parter. That means the rule has two components to it.

1 - You can use a comma when you have a modifier.

Remember we're looking for reasons TO use a comma. If you don't have one of these four reasons to use a comma, you can't use a comma. Therefore, you have to leave the comma out.

2 - Modifiers must modify the thing they are modifying.

Might seem pretty straightforward. Once you learn this rule, it is actually as straightforward as it seems. But this rule costs students several points on the ACT® because they're unaware of what it means for the ACT® English Section.

Consider this example:

Bob found his watch walking to the bathroom.

We can quickly diagram the sentence. Bob is the subject. What is he doing? Finding. Bob finds. Bob found.

Okay, got it. So the "walking to the bathroom" portion is a modifier. What is it modifying? You might say Bob, because that makes sense. Watches can't walk. But that's not grammatically what the sentence is saying.

The modifier at the end of the sentence is modifying the watch, not Bob. Sound crazy? You'll see questions asking you about this rule on every single ACT® . They're testing you on the difference between using a comma for a modifier vs. not using a comma for a modifier.

Here's the rule: A modifier at the end of a sentence with a comma modifies the subject. A modifier at the end of a sentence without a comma does NOT modify the subject.

In the sentence "Bob found his watch walking to the bathroom," grammatically Bob is finding his watch while it is walking to the bathroom. That's nonsense since watches can't walk. To make this sentence read grammatically as the writer probably intended, all we need to do is add a comma to make the modifier refer back to the subject, Bob.

So in this case, it wasn't sufficient to have a modifier to use a comma. We also needed to ensure that the modifier was modifying the correct thing. To make the comma refer back to Bob, the only thing that can walk in the sentence, we had to use a comma. So that makes sense.

They'll ask you about modifiers and commas in a variety of ways. Another way they'll test you on the usage of this rule is as follows:

Walking to the bathroom, Bob found his watch. Same sentence, just flipped the modifier to the beginning. That works, right? Comma makes the modifier refer to the subject, which is Bob… so Bob is walking to the bathroom and finding his watch. Alright, good. Great. That works!

What about this sentence:

Walking to the bathroom, Bob's watch was found.

Does this sentence work? The modifier is modifying Bob's watch, which is not the same thing as Bob. Don't worry if you didn't get this one right. I set up this example because many students aren't aware of the difference. The ACT® asks this question this way all the time.

So Bob is not Bob's watch. How do we fix it? Well, we just need Bob to be the subject so he takes the action of the walking. Walking to the bathroom, Bob found his watch. That works! It's a small, subtle change that makes a world of difference when it comes to meaning.

Extra Information

Put simply, you need to use commas whenever there is extra information. The qualification for extra information is that the sentence would make sense - grammatically and logically - if the information used was omitted. If that's true, then you can call the information "extra." In which case, it needs to be wrapped in double commas. For instance, in the sentence 'My brother, who is a doctor, lives in New York,' the phrase 'who is a doctor' is extra information.

Now, sometimes extra information comes at the end of a sentence, such as this clause at the end of this sentence. Does that mean I need to end it with a comma AND a period? You see I didn't, so I'm certain you know the answer to that question is an emphatic no. You do not use a comma and a period together back-to-back to end a sentence ever.

You can consider the comma to be omitted, to stick to the rule of "all extra information must have double commas," or you can expand that definition to say that "extra information needs to be separated from the sentence, whether the extra information clause has only one comma because it comes at the beginning or end of the sentence, or double commas when the clause is in the middle of the initial sentence." It's your call on how you want to remember the rule. Fundamentally those two things are the same thing.

Em Dashes

There's a further caveat to this rule. You will definitely see this on some ACT® Tests. Extra information can also be an em dash. Em dashes follow the same exact rules as above. They are for the purposes of the ACT® English section the same exact things as double commas for extra information.

The difference is you can't mix comma and em dash for extra information. So I can't say, "the test, which you are all taking - is coming up in a few months." That takes the extra information - "which you are all taking" - and mixes up the rule for extra information by adding both a comma and an em dash. You can't mix them and make extra information. Ever.

It's also worth mentioning that you can only use "which" in extra information. Above, when I used the "which," it was correct because I used it in an extra information clause. If I had used that inside the commas, which I didn't do, then it would be a misuse of the extra information rules. The word for that when you use it in extra information is "which." The distinction between the two rarely comes up. I bring it to your attention for cases when it does.

That's it for the comma rules!