I think it’s fair to say that the ACT really, really likes to test commas. I’ve never done a statistical analysis, but I’d wager that it’s around 15-20%.
But while the ACT does test commas in many different ways, the reality is that you don’t have to know every last rule governing comma usage. As long as you know the major ways in which commas are used correctly, you can probably identify when a comma is not being used correctly.
So that said, here are the contexts tested on the ACT that require you to absolutely, conclusively use a comma:
1) Before a FANBOYS (coordinating) conjunction when joining two independent clauses
Example: London is a very old city, and it contains buildings from many different eras.
2) To set off a non-essential clause that can be removed from a sentence
Example: London, which is a very old city, contains buildings from many different eras.
3) Between items in a list
Example: London contains buildings from time periods including the Middle Ages, the Renaissance, and the Victorian era. The third comma is optional, by the way. Since the sentence is correct both with and without it, you’ll never be tested on that particular usage.
4) To separate multiple adjectives whose order could be reversed
Example: London contains many interesting, eclectic neighborhoods, OR London contains many eclectic, interesting neighborhoods.
When you see a comma, ask yourself whether it’s being used in one of the above ways. If it isn’t, you can be relatively certain that you should choose an answer that doesn’t include it.
This is another one of those finicky little rules that have the potential to show up on the SAT and ACT. It’s an annoying one because it involves not one but two kinds of punctuation, in this case commas and parentheses (which aren’t tested all that frequently), but it’s not overly tricky to apply. In fact, if you look back at the previous sentence, you’ll see that I just used it.
Here’s whole rule:
It is never ok to use a comma before an open parenthesis, but it IS sometimes ok to use a comma after a close parenthesis.
In other words, the construction below is always incorrect:
Incorrect: The Caribbean Sea contains some of the world’s most stunning coral reefs, (which are home to thousands of species of marine life) but many of them are in danger because of overfishing and pollution.
It also means that you cannot do the following:
Incorrect: The Caribbean Sea contains some of the world’s most stunning coral reefs, (which are home to thousands of species of marine life), but many of them are in danger because of overfishing and pollution.
Why? Because two commas = two parentheses. Either type of punctuation can be used to set off a non-essential clause, but it is redundant to use both.
On the other hand, this is perfectly fine:
Correct: The Caribbean Sea contains some of the world’s most stunning coral reefs (which are home to thousands of species of marine life), but many of them are in danger because of overfishing and pollution.
In this case, the comma after the close-parenthesis is acceptable because a comma would be necessary if the parentheses were eliminated. In that case, we would be left with two complete sentences joined by the coordinating conjunction but — a construction that requires a comma.
Correct: The Caribbean Sea contains some of the world’s most stunning coral reefs, but many of them are in danger because of overfishing and pollution.
Most people learn that names and titles (of books, magazines, etc.) should be automatically surrounded by commas, but in fact that’s not quite true. It actually depends on the circumstances, and having a comma vs. no comma can drastically change the meaning of a sentence.
This is a rule that is best discussed through examples, so here goes. Consider the following sentence:
With Commas: Last night, James and his friend, Peter, went to see a movie.
The commas around the word Peter tell us that we are talking about one specific friend, and that the friend is named Peter. Taken out of context, it can also imply that James has only one friend, and that the friend is named Peter.
Now let’s look at the sentence without commas:
No Commas: Last night, James and his friend Peter went to see a movie.
This sentence means that Peter is one of multiple friends that James has, and that James went to the movies last night with the friend named Peter.
One more example:
With Commas: Michael Pollan’s book, In Defense of Food, has caused many people to examine closely the ingredients of the foods they eat.
The commas indicate that we are talking about one specific book by Michael Pollan: In Defense of Food.
No Commas: Michael Pollan’s book In Defense of Food has caused many people to examine closely the ingredients of the foods they eat.
This version means that Michael Pollan has written multiple books and that we are talking about the one that happens to be entitled In Defense of Food. Make sense? This rule can be tricky when it appears because it requires you to actually thinking about the meaning — and the implication — of a sentence instead of just automatically applying a rule. Questions covering it don’t appear on every on ACT, but they’ll show up often enough to make the rule worth your while to learn.
This is one of the most common errors involving commas on the ACT, and it’s one that’s very easy to identify and fix.
A compound item is simply two nouns or verbs joined by the word “and.” The rule is that you never need a comma before the “and.”
If the grammatical terminology makes you too nervous, there’s also a great shortcut: comma + and = period, and if you plug in a period, you won’t have two full sentences. Since the period isn’t correct, “comma + and” isn’t correct either.
Compound Subject Errors
Incorrect: The cover, and the binding of the old book are beginning to disintegrate.
Period replaces “comma + and:” The cover. The binding of the old book are beginning to disintegrate.
Correct: The cover and the binding of the old book are beginning to disintegrate.
Compound Object Errors
Incorrect: The book has many pages, and illustrations.
Period replaces “comma + and:” The book has many pages. Illustrations.
Correct: The book has many pages and illustrations.
Incorrect: The cover of the old book is beginning to fade, and disintegrate.
Period replaces “comma + and:” The cover of the old book is beginning to fade. Disintegrate.
Correct: The cover of the old book is beginning to fade and disintegrate.
Questions that look like the following appear on the English portion of virtually every ACT:
What do you get when you cross a chicken with an apple? A daffodil with rice? A flounder with a tomato? These aren’t jokes, waiting for a punch line.
A. NO CHANGE
B. jokes waiting
C. jokes, waiting
D. jokes, waiting,
Although this appears to be a question about commas, it’s actually about something else entirely: relative clauses. Now, the term “relative clause” is one that I avoid whenever possible; it tends to make people a little bit nervous. It also sounds kind of icky and grammatical, the sort of thing that’s so absurdly complicated that it makes you want to throw up your hands in utter defeat before you’ve even started to try to understand what it is.
Here’s the thing, though: relative clauses aren’t actually that hard. And in order to be certain about these questions — which can be among the trickiest English questions on the ACT — it really helps to understand the basic grammar behind them.
Relative pronouns are words like which, who(se), and that. They are frequently used to connect two sentences that would sound stiff and unnecessarily repetitive when written separately.
Without relative pronoun: I saw a man. The man was eating a hamburger.
With relative pronoun: I saw a man who was eating a hamburger.
Without relative pronoun: This is the book. I read the book yesterday.
With relative pronoun: This is the book that I read yesterday.
It is also possible to join the sentences and create a relative clause without using a relative pronoun. For example:
Correct: I saw a man who was eating a hamburger.
Correct: This is the book that I read yesterday.
When you get rid of the relative pronoun, however, you do not ever need to replace it with a comma — but this is exactly what the ACT does. And in the vast majority of instances, the pronoun in question will be that:
Correct: This is the book that I read yesterday
Correct: This is the book I read yesterday
Incorrect: This is the book, I read yesterday.
Which brings us back to the original question. The underlined portion of the sentence is in fact a relative clause. It could have also been written this way:
These aren’t jokes that are waiting for a punch line.
But since the relative pronoun that doesn’t appear in the sentence, no comma is necessary. The answer is therefore B (“These aren’t jokes waiting for a punchline.”)
Recognizing these questions can take a little bit of thought — they’re easy to overlook if you’re not expecting them to be there. But since there’s at least one on pretty much every single test, learning to recognize them can get you a guaranteed point or two.