5th Grade Writing Quiz: Use Commas With Introductory Elements

What this quiz covers

This quiz focuses on Use Commas With Introductory Elements, giving you a quick way to practice the rules, question types, and explanations that matter most for 5th Grade Writing.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. However, we still finished, the science project on time.
2. However, we still finished the science project on time. (correct answer)
3. However we still finished the science project on time.
4. However we still finished, the science project on time.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with an introductory word: 'However'. This provides transition/contrast context for the main sentence. The main clause begins with 'we still finished'. Choice B is correct because it places the comma immediately after the introductory element 'However,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'However, we still finished the science project on time.' Choice D represents multiple commas error. This error adds an unnecessary comma within the main clause, breaking sentence incorrectly. Students make this error when they confuse introductory commas with series commas. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside). Use hand motion: introduction (hand up), comma (pause), main clause (hand down). Watch for: omitting comma entirely (most common), placing comma within introductory element instead of after it.

Question 2

1. In, the morning we pack our backpacks before leaving.
2. In the morning we pack our backpacks, before leaving.
3. In the morning, we pack our backpacks before leaving. (correct answer)
4. In the morning, we, pack our backpacks before leaving.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'In the morning'. This provides time context for the main sentence. The main clause begins with 'we pack'. Choice C is correct because it places the comma immediately after the introductory element 'In the morning,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'In the morning, we pack our backpacks before leaving.' Choice A represents a comma placed within the introductory phrase error. This error breaks the introductory phrase incorrectly and confuses readers. Students make this error when they place commas by feel rather than understanding the complete introductory element. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Watch for: omitting comma entirely (most common), placing comma within introductory element instead of after it, confusing introductory commas with series commas.

Question 3

1. If we finish early we can play a quick game outside.
2. If, we finish early we can play a quick game outside.
3. If we finish early, we can play a quick game outside. (correct answer)
4. If we finish early we can, play a quick game outside.

Explanation: An introductory clause like "If we finish early" should be followed by a comma before the main part of the sentence. Choice C places the comma after "early," so it is correct. Choice A has no comma, Choice B puts it after "If," and Choice D puts it after "can," so none punctuates the introductory clause correctly.

Question 4

1. If, you finish your homework you can play a board game.
2. If you finish your homework you can play a board game.
3. If you finish your homework, you can play a board game. (correct answer)
4. If you finish your homework you, can play a board game.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a dependent clause: 'If you finish your homework'. This provides condition context for the main sentence. The main clause begins with 'you can play'. Choice A is correct because it places the comma immediately after the introductory element 'If you finish your homework,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'If you finish your homework, you can play a board game.' Choice D represents missing comma error. This error makes sentence harder to read and obscures where introduction ends. Students make this error when they don't recognize introductory elements, especially dependent clauses. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Have students identify the subject and verb of main clause - comma goes before these. Remember: even SHORT introductory phrases should have comma in 5th grade writing.

Question 5

1. When the bell rang, Jamal lined up with his class. (correct answer)
2. When the bell rang Jamal lined up with his class.
3. When the bell, rang Jamal lined up with his class.
4. When the bell rang Jamal, lined up with his class.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a dependent clause: 'When the bell rang'. This provides time/condition context for the main sentence. The main clause begins with 'Jamal lined up'. Choice A is correct because it places the comma immediately after the introductory element 'When the bell rang,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'When the bell rang, Jamal lined up with his class.' Choice B represents a missing comma error. This error makes it unclear where the introductory clause ends and the main clause begins. Students make this error when they don't recognize dependent clauses as introductory elements needing commas. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Have students identify the subject and verb of main clause - comma goes before these.

Question 6

1. However we decided to practice basketball inside the gym.
2. However, we decided to practice basketball inside the gym. (correct answer)
3. However, we, decided to practice basketball inside the gym.
4. However we, decided to practice basketball inside the gym.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with an introductory word: 'However'. This provides contrast context for the main sentence. The main clause begins with 'we decided'. Choice B is correct because it places the comma immediately after the introductory element 'However,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'However, we decided to practice basketball inside the gym.' Choice A represents missing comma error. This error makes sentence harder to read and obscures where introduction ends. Students make this error when they don't recognize introductory elements, especially transition words. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Have students identify the subject and verb of main clause - comma goes before these. Watch for: omitting comma entirely (most common), placing comma within introductory element instead of after it, confusing introductory commas with series commas.

Question 7

1. Before dinner, Chen washed his hands and set the table. (correct answer)
2. Before, dinner Chen washed his hands and set the table.
3. Before dinner Chen washed, his hands and set the table.
4. Before dinner Chen, washed his hands and set the table.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'Before dinner'. This provides time context for the main sentence. The main clause begins with 'Chen washed'. Choice A is correct because it places the comma immediately after the introductory element 'Before dinner,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'Before dinner, Chen washed his hands and set the table.' Choice B represents comma in wrong place error. This error breaks the prepositional phrase incorrectly by placing comma after 'Before' instead of after the complete phrase. Students make this error when they put comma after first word only when phrase is longer. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: prepositional phrases starting sentences (In the morning, After school, Under the tree, Before dinner). Have students identify the subject and verb of main clause - comma goes before these.

Question 8

1. Walking carefully Amir carried the glass of water to the sink.
2. Walking, carefully Amir carried the glass of water to the sink.
3. Walking carefully, Amir carried the glass of water to the sink. (correct answer)
4. Walking carefully Amir, carried the glass of water to the sink.

Explanation: The introductory phrase "Walking carefully" should be followed by a comma before the main part of the sentence. Choice C places the comma after "carefully," so it is correct. Choice A has no comma, Choice B breaks up the phrase, and Choice D puts the comma after "Amir," so none separates the introductory phrase correctly.

Question 9

1. Suddenly, the lights went out during our class play rehearsal. (correct answer)
2. Suddenly the lights went out during our class play rehearsal.
3. Suddenly the lights, went out during our class play rehearsal.
4. , Suddenly the lights went out during our class play rehearsal.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with an introductory word: 'Suddenly'. This provides manner context for the main sentence. The main clause begins with 'the lights went out'. Choice A is correct because it places the comma immediately after the introductory element 'Suddenly,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'Suddenly, main clause.' Choice B represents the missing comma error. This error makes the sentence harder to read and fails to signal the pause after the introductory word. Students make this error when they don't recognize single-word introductory elements need commas too. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Use hand motion: introduction (hand up), comma (pause), main clause (hand down).

Question 10

1. However we decided to keep practicing for the basketball game.
2. However, we decided to keep practicing for the basketball game. (correct answer)
3. However we, decided to keep practicing for the basketball game.
4. However we decided, to keep practicing for the basketball game.

Explanation: The introductory word "However" at the start of a sentence should be followed by a comma. Choice B places the comma right after "However," so it is correct. Choice A has no comma, Choice C puts it after "we," and Choice D puts it after "decided," so none is right.

Question 11

1. During, lunch Sofia traded her apple for a granola bar.
2. During lunch Sofia, traded her apple for a granola bar.
3. During lunch Sofia traded her apple for a granola bar.
4. During lunch, Sofia traded her apple for a granola bar. (correct answer)

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'During lunch'. This provides time context for the main sentence. The main clause begins with 'Sofia traded'. Choice C is correct because it places the comma immediately after the introductory element 'During lunch,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'During lunch, Sofia traded her apple for a granola bar.' Choice A represents missing comma error. This error makes sentence harder to read and obscures where introduction ends. Students make this error when they don't recognize introductory elements. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: prepositional phrases starting sentences (In the morning, After school, During lunch). Remember: even SHORT introductory phrases should have comma in 5th grade writing.

Question 12

1. In the library, Maya found a book about planets. (correct answer)
2. In, the library Maya found a book about planets.
3. In the library Maya, found a book about planets.
4. In the library Maya found, a book about planets.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'In the library'. This provides location context for the main sentence. The main clause begins with 'Maya found'. Choice A is correct because it places the comma immediately after the introductory element 'In the library,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'In the library, Maya found a book about planets.' Choice B represents comma in wrong place error. This error breaks the prepositional phrase incorrectly by placing comma after 'In' instead of after the complete phrase. Students make this error when they confuse with other comma uses. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree). Remember: even SHORT introductory phrases should have comma in 5th grade writing.

Question 13

1. Suddenly the lights went out during the movie.
2. Suddenly the lights, went out during the movie.
3. ,Suddenly the lights went out during the movie.
4. Suddenly, the lights went out during the movie. (correct answer)

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with an introductory word: 'Suddenly'. This provides time context for the main sentence. The main clause begins with 'the lights went out'. Choice C is correct because it places the comma immediately after the introductory element 'Suddenly,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'Suddenly, the lights went out during the movie.' Choice A represents missing comma error. This error makes sentence harder to read and obscures where introduction ends. Students make this error when they don't recognize introductory elements. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Use hand motion: introduction (hand up), comma (pause), main clause (hand down).

Question 14

1. After school, we practiced soccer in the field. (correct answer)
2. After school we, practiced soccer in the field.
3. After school we practiced, soccer in the field.
4. After, school we practiced soccer in the field.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'After school'. This provides time context for the main sentence. The main clause begins with 'we practiced'. Choice B is correct because it places the comma immediately after the introductory element 'After school,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'After school, we practiced soccer in the field.' Choice A represents comma in wrong place error. This error breaks the subject-verb connection by placing comma between 'we' and 'practiced', which disrupts the main clause. Students make this error when they place comma by feel rather than rule. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Have students identify the subject and verb of main clause - comma goes before these.

Question 15

1. Because it was windy, Jamal flew his kite near the beach. (correct answer)
2. Because, it was windy Jamal flew his kite near the beach.
3. Because it was windy Jamal, flew his kite near the beach.
4. Because it was windy Jamal flew, his kite near the beach.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a dependent clause: 'Because it was windy'. This provides cause/reason context for the main sentence. The main clause begins with 'Jamal flew'. Choice A is correct because it places the comma immediately after the introductory element 'Because it was windy,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'Because it was windy, Jamal flew his kite near the beach.' Choice B represents comma in wrong place error. This error breaks the dependent clause incorrectly by placing comma after 'Because' instead of after the complete introductory clause. Students make this error when they don't recognize complete introductory elements. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: dependent clauses (When..., If..., Because..., Although...). Watch for: placing comma within introductory element instead of after it.

Question 16

1. After, school we finished our science project in the library.
2. , After school we finished our science project in the library.
3. After school we, finished our science project in the library.
4. After school, we finished our science project in the library. (correct answer)

Explanation: The introductory phrase "After school" should be followed by a comma before the main part of the sentence. Choice D places the comma after "school," so it is correct. Choice A splits "After school," Choice B puts the comma at the very start, and Choice C puts it after "we," so none punctuates the introductory phrase correctly.

Question 17

1. Carefully Chen, carried the glass jar to the counter.
2. Carefully Chen carried the glass jar to the counter.
3. , Carefully Chen carried the glass jar to the counter.
4. Carefully, Chen carried the glass jar to the counter. (correct answer)

Explanation: An introductory element is a word or group of words that begins a sentence and gives us extra information before we get to the main idea. When you use one, you set it off with a comma to show where the introduction ends and the rest of the sentence begins. Here's how to find the right spot. First, look at the beginning of the sentence for that introductory word: "Carefully." Next, ask yourself where the introduction stops and the main part starts. The main part is "Chen carried the glass jar to the counter." So the comma belongs right after "Carefully." That's why "Carefully, Chen carried the glass jar to the counter." is correct—the comma sits neatly between the introduction and the rest. Try this: write a sentence starting with a word like "Quietly" or "Suddenly," then drop a comma right after it before the rest of your sentence!

Question 18

1. Before dinner, Chen fed the dog and set the table. (correct answer)
2. Before dinner Chen fed the dog and set the table.
3. Before, dinner Chen fed the dog and set the table.
4. Before dinner Chen, fed the dog and set the table.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'Before dinner'. This provides time context for the main sentence. The main clause begins with 'Chen fed'. Choice A is correct because it places the comma immediately after the introductory element 'Before dinner,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'Before dinner, Chen fed the dog and set the table.' Choice B represents a missing comma error. This error fails to separate the time phrase from the main actions, making the sentence harder to read. Students make this error when they don't recognize prepositional phrases as introductory elements. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Have students identify the subject and verb of main clause - comma goes before these.

Question 19

1. Suddenly the lights flickered during the class movie.
2. Suddenly, the lights flickered during the class movie. (correct answer)
3. Suddenly the lights flickered, during the class movie.
4. Suddenly the lights, flickered during the class movie.

Explanation: The introductory word "Suddenly" should be followed by a comma before the rest of the sentence. Choice B places the comma right after "Suddenly," so it is correct. Choice A has no comma, Choice C puts it before "during," and Choice D puts it after "lights," so none punctuates the introductory word correctly.

Question 20

1. At the park, Sofia and Chen raced their scooters along the path. (correct answer)
2. At the park Sofia and Chen raced their scooters along the path.
3. At, the park Sofia and Chen raced their scooters along the path.
4. At the park Sofia and Chen raced, their scooters along the path.

Explanation: This question tests CCSS.L.5.2.b: using a comma to separate an introductory element from the rest of the sentence. An introductory element comes at the beginning of a sentence and provides context about when, where, why, how, or under what conditions the main action occurs. A comma is placed immediately after the introductory element to separate it from the main clause. Types include: single words (Yesterday, However), prepositional phrases (In the morning, After school), and dependent clauses (When it rains, If you finish). This sentence begins with a prepositional phrase: 'At the park'. This provides location context for the main sentence. The main clause begins with 'Sofia and Chen raced'. Choice A is correct because it places the comma immediately after the introductory element 'At the park,', separating it from the main clause. The comma signals the shift from introductory context to the main idea, making the sentence structure clear: 'At the park, main clause.' Choice B represents the missing comma error. This error makes the sentence harder to read and obscures where the location context ends. Students make this error when they don't recognize prepositional phrases as introductory elements. To help students: Teach them to identify introductory elements by asking 'What comes before the main idea?' or 'What gives context for the sentence?' Practice underlining or bracketing the introductory element, then placing comma after it before the main clause. Create formula: [Introductory element], [main clause]. Common introductory patterns: single transition words (However, Therefore), time/place words (Yesterday, Outside), prepositional phrases starting sentences (In the morning, After school, Under the tree), dependent clauses (When..., If..., Because..., Although...). Use hand motion: introduction (hand up), comma (pause), main clause (hand down).