Why it matters on the HSPT
Punctuation items ask you to find the sentence with a punctuation error, or to choose no mistakes, and commas are the punctuation mark most often at stake. A sentence can sound perfectly natural with a comma missing or a comma added, which is exactly why the test uses commas: your ear will not catch it, so you need the rules. Commas also decide several composition items, where a choice is wrong only because of a comma splice.
The rules
1. Between items in a series. Three or more items get commas between them: pencils, paper, and a ruler. Two items joined by and get no comma: pencils and paper.
2. Before a joining word that connects two complete sentences. The joining words are and, but, or, nor, for, so, yet. The rule needs both halves to stand alone as sentences. The bus was late, so we walked. Both halves have a subject and a verb. If the second half shares the subject of the first, there is no comma: the bus was late and made us walk. That is one subject, bus, with two verbs.
3. After an introductory word, phrase, or clause. After the game, we ate. However, the store was closed. When the bell rang, everyone stood. Anything that comes before the main sentence and sets it up gets a comma after it.
4. Around information the sentence does not need. My uncle, who lives in Denver, called last night. Take out who lives in Denver and the sentence still makes sense, so it sits between commas. Compare: the uncle who lives in Denver called, and the other did not. Now the clause tells you which uncle, so no commas. The same rule covers appositives, which rename a noun: our teacher, Ms. Ortiz, was out.
5. With direct address and interrupters. Thanks, Dad. Dad, where are the keys? The answer, of course, was no.
6. In dates, addresses, and letters. July 4, 1776, was a Thursday. She moved to Austin, Texas, last spring. Dear Grandma, and Sincerely, each take a comma.
Two places a comma never goes. Never between a subject and its verb: the girl in the red coat waved, not the girl in the red coat, waved. Never between a verb and its object: he said that he was tired, not he said, that he was tired.
The comma splice. Two complete sentences cannot be joined by a comma alone. The lights went out, everyone gasped is a splice. Fix it three ways: a period, a semicolon, or a comma plus a joining word. The test's favorite version is a splice with however in the middle: it rained, however we still played. However is not a joining word; that sentence needs a semicolon or a period before however.
Worked examples
Example 1
Which sentence contains an error in punctuation?
A. We packed sandwiches, apples, and water.
B. She wanted to go but her mother said no.
C. After the storm, the street was covered in branches.
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: B: B
But joins two complete sentences, she wanted to go and her mother said no, so a comma belongs before it. Sentence A has a correct series, and sentence C has a correct introductory phrase.
Example 2
Which sentence contains an error in punctuation?
A. The twins bedroom overlooks the alley.
B. My grandfather, who is eighty, still swims every morning.
C. The dog barked, and the cat ran under the bed.
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: A: A
Sentence A is missing an apostrophe, not a comma, but it is still the sentence with the error: it should be the twins' bedroom. Sentence B correctly sets off a clause the sentence does not need. Sentence C correctly joins two complete sentences with a comma and and.
Example 3
Which sentence contains an error in punctuation?
A. The boy in the blue jacket, is my cousin.
B. Yes, I finished the assignment.
C. Kwame answered, 'I finished last night.'
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: A: A
The comma in sentence A separates the subject, boy, from its verb, is. Nothing ever goes between a subject and its verb. Sentence B correctly follows an introductory yes with a comma, and sentence C correctly introduces a quotation.
Example 4
Which sentence contains an error in punctuation?
A. The museum opens at nine, however, the gift shop opens at ten.
B. We visited Portland, Oregon, in June.
C. Dad, can you drive us to practice?
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: A: A
Sentence A is a comma splice. Two complete sentences are joined by however with only commas, and however cannot join sentences. It needs a semicolon or a period before however. Sentences B and C follow the address and direct address rules.
Example 5
Which sentence contains an error in punctuation?
A. She painted the fence and then washed the brushes.
B. The teacher who runs the chess club, is retiring.
C. Before you leave, lock the back door.
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: B: B
The clause who runs the chess club tells you which teacher, so it is needed and takes no commas at all. The single comma after club also splits the subject from its verb. Sentence A has one subject with two verbs, so no comma is needed before and.
Example 6
Which sentence contains an error in punctuation?
A. The recipe calls for flour, sugar butter, and two eggs.
B. Our neighbor, Mr. Lin, grows tomatoes.
C. It was cold, so we built a fire.
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: A: A
The series is missing the comma between sugar and butter, which turns them into one strange item. Sentence B correctly sets off an appositive. Sentence C correctly joins two complete sentences with a comma and so.
Example 7
Which sentence contains an error in punctuation?
A. The concert ended late, we missed the last train.
B. On Saturday, the library opens at ten.
C. I brought a jacket, but I never needed it.
D. No mistakes.
- A.A
- B.B
- C.C
- D.D
Show answer
Answer: A: A
Sentence A joins two complete sentences with only a comma, a comma splice. It needs a period, a semicolon, or a comma plus so. Sentence B has a correct introductory phrase, and sentence C correctly uses a comma before but.
Common mistakes
- Adding a comma wherever you would pause. Pauses are not the rule. Subject and verb never get a comma between them no matter how long the subject is.
- Missing the comma before and, but, or so when both halves are full sentences. Check for a second subject.
- Adding that comma when there is only one subject. She ran and jumped needs no comma.
- Treating however as a joining word. It is not. A comma before it between two sentences is a splice.
- Cutting off a needed clause. If removing the clause changes which person or thing you mean, it needs no commas.
Practice
Comma rules decide most punctuation items and the splice traps in composition. The subject-verb agreement lesson covers the usage errors that appear alongside them.