Over the course of 15+ years of working one-on-one with high schoolers to send their ACT scores soaring, I’ve noticed something amazing: just two areas of grammar account for MOST of the points that students lose on the ACT English section.
If there are just two specific subtopics that tend to cost students points…it’s obvious what we need to do! Today’s post will help make sure you know how to spot these two grammar hurdles on the ACT…and how to clear them easily while other test-takers stumble.
Article Contents
1. Video version of this article
2. Structure of the ACT English
3. Mistake #1: thinking the subject is in a prepositional phrase
4. Mistake #2: connecting two complete clauses with a comma
5. Conclusion
Video version of this article:
Structure of the Enhanced ACT English Section
The layout of the new (“enhanced”) ACT English section is relatively simple:
50 questions total are distributed across 6 passages.
4 of those passages will be attached to 10 questions each.
The other 2 passages have 5 questions each.
One of the 10-question passages will be experimental and not count towards your score. However, you won’t know which one it is.
Note that this question breakdown differs from the old, non-enhanced version of the ACT, which was discontinued in April 2025.
All passages are about the same difficulty level, and the questions about a given passage are randomized by difficulty. In other words, no passage is meant to be any harder than another—and within a passage, there is no consistent rule that determines which questions are harder or easier. (Note that this contrasts with the ACT Math!) You may get a tough question, followed by a few softballs, then a medium, then another toughie.
As for the actual content of those Qs, the ACT English comprises a mixture of straight-up grammar questions and Qs about rhetorical devices. More questions will be dedicated to grammar, however.
Top ACT English mistake #1: thinking the subject is in a prepositional phrase
Subject-verb agreement questions comprise a solid portion of the ACT English. Most native English speakers can typically follow their intuition towards the appropriate form of a verb to match the subject. (Typically….but not always on the ACT! Which is what I’ll explain in a moment.)
For example, if you grew up speaking English and hear someone say “the frog sing,” you’d naturally just hear that something was off, even if you couldn’t put your finger on why right away. When you zoom in a bit, you’ll notice that the “offness” comes from the fact that there’s a singular subject (i.e. “the frog”), which should be accompanied by a singular verb—and singular verbs usually end with an “s” (i.e. “sings” rather than “sing”).
That part’s easy. The hard part is correctly identifying the subject of a given sentence…so that you can know what you’re matching the verb conjugation to!
There are 6 main ways the ACT might try to sneakily hide the subject. But the single sneakiest, trickiest one—AND the one that pops up the most frequently?
Confusing you with a prepositional phrase.
Here's an example of a sentence the ACT might give you:
One of the staplers are blue.
In this sentence, many students will mistakenly think the subject is the word “staplers.” However, if we look closely, the word “staplers” has cropped up in a phrase that starts with “of”—and “of” is a preposition.
The rule of thumb you need to remember here is that the subject is NEVER found in a prepositional phrase.
So here’s a hack that works for my students. Simply cross out the phrase starting with the preposition, e.g.:
One
of the staplersare blue.
Now, it’s easy to see that the subject is the only noun left: “One”! (Which is singular, of course.)
Thus, the correct sentence looks like this:
One of the staplers is blue.
The reason this is sneaky is that if we rely on our ears, we hear “staplers are” and that seems right. That’s exactly what the ACT wants you to hear, and to think. That’s why they make sure that the noun at the end of the prepositional phrase does NOT match the number of the real subject—the one they’re trying to hide. In other words, if the real subject is singular, the noun at the end of the prepositional phrase will likely be plural, and vice versa.
So you have to lean a little more on your knowledge of the abstract rules—and identify the subject with your brain, not just your ears.
Frequent error #2 on the New ACT: comma splice.
So before we get into why this is wrong, let’s first revisit what a “clause” is to begin with. It’s just a set of words that contains both a subject and a verb.
Some clauses can stand on their own. I call these “independent clauses” or “complete clauses”:
Grace drinks horchata.
Then again, some clauses CANNOT stand on their own. They become fragments when you remove the second clause. I refer to these as either “dependent clauses” or “incomplete clauses”:
If Grace drinks horchata. Nope! Your ears/eyes are probably giving you the gut feeling that this clause could NOT be its own sentence.
There are several acceptable ways to combine two complete clauses, as well as several acceptable ways to combine an independent/complete clause with a dependent/incomplete clause. However, here’s what can NEVER happen, and what the ACT loves to try to trick you with:
You CANNOT join a complete clause with another complete clause using only a comma! If you make that mistake, known as a “run-on sentence” or “comma splice,” you’ll have to walk the Grammar plank, matey.
Grace is thirsty, she drinks two horchatas.
^^^ Oops. You’ve just created a run-on sentence. Please don’t commit this grammar sin!
So, how do you go about fixing this one? There are several ways, luckily, and the ACT isn’t picky.
A) Make them 2 separate sentences:
Grace is thirsty. She drinks two horchatas.
B) Combine them with a comma AND a FANBOYS conjunction (“For And Nor But Or Yet So”):
Grace is thirsty, so she drinks two horchatas.
C) Combine them with a semi-colon. However, in this case, be careful NOT to use a FANBOYS conjunction!
Grace is thirsty; she drinks two horchatas.
D) Combine them with a colon. This one is a bit trickier to nail, though still perfectly acceptable if you do it correctly. It ONLY works if the second clause answers or clarifies a question that the first clause raises.
In this case, the example with our thirsty friend Grace doesn’t really work, so let’s try a new example:
Magnus wouldn’t find out until Friday why he didn’t get the job: he had written the incorrect company name in his cover letter.
When we read that, our response after the first sentence is “Oooooh! Tell me! WHY didn’t he get the job?” That’s why we use a colon. The second part answers the question we’re all asking after reading the first complete clause.
Make sense?
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Conclusion
These two lessons might seem minor, but I promise you, they are among the ACT’s top tricks to pull on students. Not YOU, though—not any longer! Just by taking five minutes to learn to identify those two mistakes and correct them, you’ve likely gained a multi-point increase. That’s a real gain for just (re-)learning two rules.
And speaking of good bang for your buck: if you want more all-killer-no-filler guidance on the ACT English section, check out my Cram Plan on the subject. This PDF leads you through exactly what you need to know for this part of the ACT—as quickly as possible.
