Punctuation Quiz #5: Colons

By Mark Nichol

All but one of the following sentences demonstrate incorrect use of the colon; revise the sentences as necessary:

1. The three types of rock are: igneous, sedimentary, and metamorphic.

2. That’s the key: What to do about rust.

3. Try the following steps: Rinse, lather, and repeat.

4. Smith said: “That’s the way I look at it.”

5. For example: Compare the two images below.

Answers and Explanations

The function of a colon is to separate two phrases or clauses when the second element amplifies or illustrates the first element.

1.
Original: The three types of rock are: igneous, sedimentary, and metamorphic.
Correct : The three types of rock are igneous, sedimentary, and metamorphic.

A colon is redundant to a verb and should never follow one.

2.
Original: That’s the key: What to do about rust.
Correct : That’s the key: what to do about rust.

Do not capitalize the first word of a phrase or an incomplete sentence that follows a colon unless it is a proper noun. (Some style guides recommend capitalizing the first word following a colon only when the explanatory content consists of two or more sentences. However, others consider that suggestion too restrictive and advise capitalizing one or more complete explanatory sentences; I endorse this style.)

3.
Original: Try the following steps: Rinse, lather, and repeat.
Correct : Try the following steps: Rinse, lather, and repeat.

The imperative statement following the colon is a complete thought; this sentence is correct.

4.
Original: Smith said: “That’s the way I look at it.”
Correct : Smith said, “That’s the way I look at it.”

An attribution should be followed by a comma, not a colon. (Exception: Use a colon if the attribution is a complete thought, as in “Smith summed up his viewpoint tersely: “That’s the way I look at it.”)

5.
Original: For example: Compare the two images below.
Correct : For example, compare the two images below.

Always use a comma, not a colon, after an introductory phrase.

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3 Responses to “Punctuation Quiz #5: Colons”

  • Matia

    I really find it confusing to understand: do we put a comma before the “and” between the two last items of a list, like you did in the first and third sentences — that’s, after “sedimentary” and after “lather”? I always omitted it. Was I wrong all this time?

  • Mark Nichol

    Matia:
    The short answer is, either way is correct, but be consistent. Here’s a previous DailyWritingTips.com post about the topic.

  • Matia

    Mark, thanks for the response on the word “and”. It really helped!

    However, if you or anyone can still help, I have another question: Is “A colon is redundant to a verb and should never follow one.” a without-exception rule?
    Would I, therefore, be wrong to write, “You may also like: Daily Writing Tips, Uncle Google, and Grammar Girl.” Or, “The main areas to cover are: Kyotera through Kasasa, Kakuuto through Kalungi, and Rakai through Kibale.”?
    (The colon that follows the verbs “like” and “are” is redundant?)
    ,,

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