Colons, Dashes and Semicolons

American Diploma › Digital SAT Reading and Writing — Complete Course

What this question type tests

Colons, dashes and semicolons are tested in the Boundaries skill of the Standard English Conventions domain (about 26% of the scored Reading and Writing questions, 11–15 questions). These marks appear in questions about linking clauses, separating list items and setting off supplements — and in many questions they are the *wrong* answers, placed in the choices to trap students who use them “for style.”

The question looks like every other conventions item: a short passage (25–150 words) with a blank, and the stem “Which choice completes the text so that it conforms to the conventions of Standard English?” The four choices often show four different marks in the same place — for example “ingredients,” / “ingredients;” / “ingredients:” / “ingredients” — and you must know exactly what each mark is allowed to do.

This page goes deeper than the Sentence Boundaries page. You will learn each mark's jobs, the one extra semicolon rule that the SAT and ACT use, and a clear method for choosing between , ; : — when more than one looks possible.

The colon ( : )

The rule: a colon comes after a complete sentence and introduces a list, an explanation, emphasis or extra information about what came before it.

The test before every colon: stop at the colon and read only the part before it. Could it end with a period? If not, the colon is wrong.

• ✗ The recipe needs: flour, water, and salt. (“The recipe needs.” is not complete — the verb has no object)
• ✗ The kit includes items such as: a map and a compass. (never after “such as,” “including,” “for example”)
• ✗ The winners were: Hana, Omar, and Rana. (never between a verb and its complement)
• ✓ The kit includes two essential items: a map and a compass.
• ✓ The winners were the following students: Hana, Omar, and Rana.

The dash ( — )

The dash has two kinds of use. Count the dashes in the sentence first.

A pair of dashes = extra information

Two dashes work exactly like a pair of commas or a pair of brackets: they set off extra (non-essential) information. The pair must match — dash … dash.

• ✓ The novel's narrator—a retired lighthouse keeper—tells the story through letters.
• ✗ The novel's narrator—a retired lighthouse keeper, tells the story through letters.
• Removal test: “The novel's narrator tells the story through letters.” ✓ still complete.

A single dash = emphasis or a sudden break

One dash is used to give emphasis to what comes after it (often at the end of a sentence), or to show a sudden break or interruption in a thought or in speech. When it is used for emphasis, the part before the dash should normally be a complete sentence — just like with a colon.

• ✓ After months of testing, the engineers finally found the cause of the failure—a single loose screw. (emphasis)
• ✓ The rare tortoise was seen in the reserve for the first time in fifty years—a sign that the protection program was working. (emphasis on the final idea)
• ✓ “I think the answer is—” Laila began, but the bell rang. (interruption in speech)
• ✓ We had planned everything perfectly—or so we thought. (sudden break)
• ✗ The engineers found—the cause of the failure. (a single dash cannot split a verb from its object)

The semicolon ( ; )

The main job (the teacher's rule): a semicolon joins two independent clauses that are closely related. Both sides must be complete sentences. If you could replace the semicolon with a period, the semicolon is correct; if you could not, it is wrong.

• ✓ Marble is a metamorphic rock; it forms when limestone is exposed to great heat and pressure.
• ✓ Some desert plants store water in their thick leaves; others store it in underground stems.
• ✓ The road was closed; as a result, the bus took a longer route. (semicolon before a conjunctive adverb)
• ✗ Because the road was closed; the bus took a longer route. (left side is a dependent clause)
• ✗ The volunteers worked through the night; because the water was rising. (right side is a dependent clause)
• ✗ The road was closed; and the bus took a longer route. (use “, and” — not a semicolon with FANBOYS)
• ✗ Many dishes; such as koshari and ful, use beans. (a semicolon cannot introduce examples)

Choosing between , ; : — when two look correct

Use this decision method. It works for almost every question where the choices offer different marks in the same place.

1. Read the part before the blank. Is it a complete sentence? If NO → ; and : are both wrong (and a single dash for emphasis is wrong too). You need a comma or nothing.
2. Read the part after the blank. Is it a complete sentence? If YES (and the left side is complete too) → , alone is wrong (comma splice). You need ; or . or , + FANBOYS — or : if the second clause explains the first.
3. If the part after is NOT a complete sentence (a list, a word, a phrase) → ; is wrong. Use : or a single — (if the left side is complete), or a comma if the phrase is extra information.
4. Is there a pair to close? If extra information opened with a comma, dash or bracket earlier, the blank must close it with the same mark.
5. Still two choices? They cannot both be correct. Look for a second difference (an extra comma, a missing word, “and” after a semicolon).

Worked examples

Worked example 1 — colon after an incomplete clause

Text: Members of a desert research expedition must carry everything they need for ten days, because there are no shops for hundreds of kilometers. The expedition's supply list included ______ water filters, solar lamps, and several kilograms of dried dates.

Which choice completes the text so that it conforms to the conventions of Standard English?

• A) included:
• B) included
• C) included;
• D) included—

Answer: B

• A) ✗ Wrong: “The expedition's supply list included” is not a complete sentence — the verb has no object. A colon cannot follow it.
• B) ✓ Correct: No punctuation: the verb “included” goes straight to its object, the list “water filters, solar lamps, and … dates.”
• C) ✗ Wrong: A semicolon needs a complete sentence on both sides; neither side is one.
• D) ✗ Wrong: A dash cannot separate a verb from its object.

Worked example 2 — SAT/ACT extra rule (semicolons in a list)

Text: An international conference for young scientists will be held in a different Arab country each year. Over the next three years, the conference will visit three cities: Luxor, Egypt ______ Amman, Jordan; and Tunis, Tunisia.

Which choice completes the text so that it conforms to the conventions of Standard English?

• A) Egypt,
• B) Egypt;
• C) Egypt:
• D) Egypt

Answer: B

• A) ✗ Wrong: Each item already contains a comma (“Luxor, Egypt”), and the text uses a semicolon later (“Jordan; and”), so this break between items must also be a semicolon.
• B) ✓ Correct: Semicolons separate list items that contain commas, and the choice is consistent with “Jordan; and Tunis.”
• C) ✗ Wrong: There is already a colon introducing the list; a second colon in the middle of the list is wrong.
• D) ✗ Wrong: With no mark, “Egypt Amman” runs two items together.

Worked example 3 — single dash for emphasis

Text: A new electric train in a factory test kept stopping without warning, and nobody could explain why. After months of testing, the engineers finally found the cause of the failure ______ a single loose screw inside the motor.

Which choice completes the text so that it conforms to the conventions of Standard English?

• A) failure;
• B) failure, it was
• C) failure—
• D) failure, which

Answer: C

• A) ✗ Wrong: After a semicolon you need a complete sentence; “a single loose screw inside the motor” is only a phrase.
• B) ✗ Wrong: “It was a single loose screw” is an independent clause joined with only a comma: comma splice.
• C) ✓ Correct: The first part is complete, and the single dash gives emphasis to the surprising answer.
• D) ✗ Wrong: “Which a single loose screw inside the motor” has no verb and makes no sense.

Worked example 4 — semicolon between two clauses

Text: Plants that live in very dry places have developed different ways of surviving long periods without rain. Some desert plants store water in their thick, fleshy leaves ______ store it in large underground stems that stay cool below the sand.

Which choice completes the text so that it conforms to the conventions of Standard English?

• A) leaves, others
• B) leaves; others
• C) leaves others
• D) leaves: others,

Answer: B

• A) ✗ Wrong: Both sides are independent clauses (“others store it …” is complete), so a comma alone makes a comma splice.
• B) ✓ Correct: A semicolon joins two closely related independent clauses.
• C) ✗ Wrong: No punctuation between two independent clauses is a run-on.
• D) ✗ Wrong: The second clause does not explain the first (it gives a second, parallel fact), and the comma after “others” wrongly separates the subject from its verb.

Practice

Twelve original SAT-style questions. Before you choose, test the left side and the right side of every blank.

All pages in this course

Start here

• The Digital SAT: Complete Overview
• Time Strategy and How to Attack Every Question

Craft and Structure

• Words in Context
• High-Value Vocabulary for SAT Reading and Writing
• Text Structure and Purpose
• Cross-Text Connections

Information and Ideas

• Central Ideas and Details
• Command of Evidence: Textual
• Command of Evidence: Quantitative
• Inferences

Standard English Conventions

• Sentence Boundaries
• Commas and Extra Information
• Colons, Dashes and Semicolons
• Subject–Verb Agreement
• Pronouns
• Verb Tense, Aspect and Finiteness
• Modifiers, Parallel Structure and Comparisons
• Plurals and Possessives

Expression of Ideas

• Transitions
• Rhetorical Synthesis (Student Notes)

Full practice tests

• Digital SAT Reading and Writing — Practice Test 1
• Digital SAT Reading and Writing — Practice Test 2
• Digital SAT Reading and Writing — Practice Test 3