ACT English Practice: Colons, Semicolons & Periods

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  • 2:03 Question 1
  • 3:08 Question 2
  • 4:45 Question 3
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Lesson Transcript
Instructor: Elizabeth Foster

Elizabeth has been involved with tutoring since high school and has a B.A. in Classics.

In this lesson, you'll work on some practice questions using three different punctuation marks that can connect or separate complete thoughts: colons, semicolons and periods.


Ready to get a bit dotty? In this lesson, you'll practice using three punctuation marks with dots: colons, semicolons and periods. They might look similar, but these three certainly aren't all the same. So, before we start the practice questions, here's a quick review of how they're all used:

  • A colon (:) is a punctuation mark used to introduce a list or an explanation.
  • A semicolon (;) is a punctuation mark used to join two complete thoughts.
  • A period (.) is a punctuation mark used to separate two complete thoughts by marking the end of a sentence.

All three can be used between two independent clauses. An independent clause is a complete thought, or a group of words that could stand alone as a sentence. You would use a period to separate two independent clauses that aren't very closely related. For example: Mark went to the store. Susie went to work. These are just two facts without much to connect them to each other, so a period is appropriate.

You'd use a semicolon to emphasize that the clauses are closely related to each other. For example: Mark lives in the suburbs; he has a house on Birch Street. Here, the second clause is giving you more details about the fact introduced in the first. Each clause could stand on its own as a complete sentence, but since they're so closely linked, a semicolon also works.

You'd use a colon if the second clause gives an explanation for the first. For example: Mark hates dogs: he was bitten once as a child and ended up in the hospital. Here, 'he was bitten once as a child' explains why 'Mark hates dogs.' Colons can also be used to introduce a list. For example: Mark has three cats: Peter, Susan and Lucy. In this lesson, you'll practice using all three in real live practice sentences.

Question 1

Ready to get started? Let's warm up with the first question:

At the corner store, Evan bought four things. Cheese, pasta, bread and butter.

(A) (the sentence is correct as it is)

(B) four things; cheese,

(C) four things: cheese,

(D) four things, cheese,

First of all, let's decide whether there's something wrong with the original. Can you spot an error here, or is it all good to go?

There's definitely something going wrong. 'Cheese, pasta, bread and butter' is not a complete sentence; it's a fragment. It doesn't have a subject or a verb. So that period in between 'four things' and 'cheese' is going to have to go, since periods separate complete sentences. So do semicolons, so we can also cross off (B).

Now we're left with (C) and (D). Which of these would you use to introduce a list: a colon or a comma? The answer's coming up, so pause the video if you need more time to think about it.

If you said (C), you were right! Remember that a colon introduces a list, so to start off the list of all the things Joe bought, we'll need to put a colon in there.

Question 2

Ready for another? How about this one?

Max went shopping this weekend, he needed to buy Christmas gifts for his family.

(A) (as it is now)

(B) this weekend: he needed to buy

(C) this weekend; needing to buy

(D) this weekend he needed to buy

How about this one: is there anything wrong here? Yes! This question has an error called a comma splice. A comma splice is when the writer tries to connect two independent clauses with nothing but a comma. In this sentence, you can see that 'Max went shopping this weekend' and 'He needed to buy Christmas gifts' are both complete thoughts, so you can't just slap a comma in there and call it done. So, what kind of punctuation mark do you use for this?

You could use either a semicolon or a colon. The semicolon would just connect the two, where using a colon would imply that the second phrase somehow clarifies or explains the first. In the answer choices you can see that (B) has a colon while (C) has a semicolon. But can you spot what else is different?

That's right: needing. In choice (C), 'he needed' is changed to 'needing,' so suddenly that second clause stops being so independent after all. 'He needed to buy Christmas presents' is a complete thought, but 'needing to buy Christmas presents' certainly isn't. So answer choice (C) doesn't work after all.

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