1. Semicolons and Colons

2. Semicolons
Semicolons are punctuation marks used to put two or more clauses together to form one big sentence.
On the ACT, a semicolon is virtually interchangeable with a period.

3. Semicolons
Use a semicolon instead of a period to connect two related independent clauses.
Just then, the woman screamed the bird jumped up and perched on her head.
The first independent clause is “Just then, the woman screamed.”
The second independent clause is “the bird jumped up and perched on her head.”

4. Semicolons
In the absence of a conjunction (these two could be connected by a comma and the word and), a semicolon is used to join the two independent clauses.
Of course, it would have been equally correct to put a period after the first independent clause, and the ACT seldom requires you to choose between the two.
Just then, the woman screamed; the bird jumped up and perched on her head.

5. Semicolons
If the underlined portion or any of the answer choices contains a semicolon, you should ask yourself whether the sentence contains two related independent clauses not joined by a conjunction.

6. Colons
Colons are usually used after a complete statement to introduce a list of related details.
The list can have many items or just one.
Maria just purchased all the camping supplies for our trip, a backpack, a sleeping bag, and a pair of hiking boots.
“Maria just purchased all the camping supplies for our trip” is the complete statement in the sentence.

7. Colons
“A backpack, a sleeping bag, and a pair of hiking boots” are the related details.
A colon belongs between the two.
Maria just purchased all the camping supplies for our trip: a backpack, a sleeping bag, and a pair of hiking boots.

8. Colons
If the underlined phrase or any of the answer choices contains a colon, you should ask yourself if a list of some kind introduced by an independent clause.
One of the ACT’s favorite tricks is to write a sentence that utilizes a colon to introduce a list, but to do so incorrectly because it follows an incomplete thought.
Look out for colons that follow the verb including the phrase such as.

9. Colons
Maria just purchased all the camping supplies for our trip, including: a backpack, a sleeping bag, and a pair of hiking boots.
In this sentence, the colon is used improperly.
By adding the word “including,” the part of the sentence preceding the colon is no longer an independent clause, and therefore, the sentence, as written, is incorrect.

10. Colons
Colons are also used to separate two independent clauses: one that presents a general thought and another that explains or expands upon the first.
I didn’t know what to do: I could either go camping or stay home and study for the ACT.

11. Work Cited
Martz, Geoff, Kim Magloire, and Theodore Silver. Cracking the ACT ed. New York: Random House, Print.