SAT Boundaries questions: run the stand-alone test

Reader question: On SAT punctuation questions, how do I know which mark goes between the two halves of the sentence?

Boundaries questions are the punctuation questions on the Digital SAT. College Board's own question bank describes them plainly: the four answer choices contain different punctuation. The question stem is always some version of: "Which choice completes the text so that it conforms to the conventions of Standard English?"

Here is the entire method. It takes about fifteen seconds per question once you practice it.

The stand-alone test

1. Find the boundary where the punctuation changes.
2. Cover the mark with your thumb. Read each side as its own sentence and ask: could this stand alone as a complete sentence?
3. Both sides stand alone? Then the mark must be a period, a semicolon, or a comma plus a joining word (and, but, or, nor, for, so, yet). A comma by itself between two complete sentences is a comma splice, and a comma splice is always wrong.
4. Only the first side stands alone? Then a period and a semicolon are both dead, because neither one can be followed by a fragment. Use a colon if a list, quotation, or explanation follows; otherwise use a comma.

That is the whole game. Most students miss these because they pick the mark that "sounds right" when read aloud. The stand-alone test replaces your ear with a rule.

SAT-style practice

Each question below is original SAT-style practice, not an official College Board item.

Question 1. The museum's new wing opened in March _ visitors have been lining up since dawn.

A) March, B) March; C) March: D) March

Answer: B. Cover the mark. "The museum's new wing opened in March" stands alone. "Visitors have been lining up since dawn" stands alone. Two complete sentences, so a comma alone is a comma splice (A is out), no punctuation at all is a run-on (D is out), and a colon is out because it promises a list, quotation, or explanation, and none of those follow. That leaves the semicolon. The tempting wrong answer is A: the pause between the two thoughts makes a comma feel natural, but a comma splice is a comma splice no matter how natural it feels.

Question 2. To improve his score, Jamal focused on three things _ timing, a guessing strategy, and an error log.

A) things: B) things; C) things, D) things

Answer: A. "To improve his score, Jamal focused on three things" stands alone. "Timing, a guessing strategy, and an error log" cannot. Only the first side stands alone, so the period-style marks are dead: a semicolon needs a complete sentence after it (B is out) and so does a period (D is out). A comma cannot introduce a list (C is out). The colon is exactly right: a complete clause followed by the list it promised. The tempting wrong answer is B, because students treat the semicolon as a fancier comma. It is not. A semicolon is a period wearing a disguise.

Question 3. Running on four hours of sleep, the students still finished the practice test _ which surprised their tutor.

A) test; B) test, C) test: D) test

Answer: B. "Running on four hours of sleep, the students still finished the practice test" stands alone. "Which surprised their tutor" cannot: "which" makes it a dependent fragment. Only the first side stands alone, so A and D are out immediately. A colon would need a list, quotation, or explanation (C is out). The comma is correct: a dependent clause attaches to the main sentence with a comma. The tempting wrong answer is A. The sentence is long, and long sentences make students reach for heavy punctuation. Run the test instead of trusting the feeling.

Drill it

Pull five Boundaries items from College Board's free student question bank and run the stand-alone test on each before looking at the choices. Name the reason out loud: "both stand alone, so no lone comma" or "second side is a fragment, so no semicolon." When you can name the reason in under ten seconds, you own this skill.