This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Emma wanted to play outside' and 'it began to rain' joined by 'but.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice B is correct because it places the comma before the coordinating conjunction 'but' in the compound sentence. The pattern is: Independent clause (Emma wanted to play outside) , but Independent clause (it began to rain). Both parts can stand alone as sentences, so comma is needed. Choice A represents comma in wrong position, which occurs when students put comma after conjunction instead of before. The comma must come BEFORE the conjunction, not after. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Marcus forgot his library book' and 'he returned it the next day' joined by 'so.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice A is correct because it places the comma before the coordinating conjunction 'so' in the compound sentence. The pattern is: Independent clause (Marcus forgot his library book) , so Independent clause (he returned it the next day). Both parts can stand alone as sentences, so comma is needed. Choice D represents adding comma in simple sentence, which occurs when students add comma in simple sentences with compound predicates thinking all sentences with 'so' need commas. Adding comma before 'so' in 'Marcus forgot his library book, so returned it the next day' is wrong because there's one subject - this is a simple sentence with compound predicate, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Yuki cleaned her desk' and 'she lined up quietly for lunch' joined by 'and.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice B is correct because it places the comma before the coordinating conjunction 'and' in the compound sentence. The pattern is: Independent clause (Yuki cleaned her desk) , and Independent clause (she lined up quietly for lunch). Both parts can stand alone as sentences, so comma is needed. Choice A represents comma in wrong position, which occurs when students put comma after conjunction instead of before. The comma must come BEFORE the conjunction, not after. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, the correct version has two independent clauses: 'Chen shared crayons' and 'Amir colored the picture during art class today' joined by 'and.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice B is correct because it places the comma before the coordinating conjunction 'and' in the compound sentence. The pattern is: Independent clause (Chen shared crayons) , and Independent clause (Amir colored the picture during art class today). Both parts can stand alone as sentences, so comma is needed. Choice A represents comma in wrong position, which occurs when students confuse compound subject/predicate with compound sentence. Adding comma in 'Chen, and Amir shared crayons' is wrong because this is a compound subject, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Amir can sit by the window' and 'he can sit near the door' joined by 'or.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice B is correct because it places the comma before the coordinating conjunction 'or' in the compound sentence. The pattern is: Independent clause (Amir can sit by the window) , or Independent clause (he can sit near the door). Both parts can stand alone as sentences, so comma is needed. Choice D represents adding comma in simple sentence, which occurs when students add comma in simple sentences with compound predicates thinking all sentences with 'or' need commas. Adding comma before 'or' in 'Amir can sit by the window, or sit near the door' is wrong because there's one subject - this is a simple sentence with compound predicate, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Carlos was thirsty' and 'he drank a glass of water after recess' joined by 'so.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice B is correct because it places the comma before the coordinating conjunction 'so' in the compound sentence. The pattern is: Independent clause (Carlos was thirsty) , so Independent clause (he drank a glass of water after recess). Both parts can stand alone as sentences, so comma is needed. Choice C represents adding comma in simple sentence, which occurs when students add comma in simple sentences with compound predicates thinking all sentences with 'so' need commas. Adding comma before 'so' in 'Carlos was thirsty, so drank a glass of water' is wrong because there's one subject - this is a simple sentence with compound predicate, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Jamal finished his math' and 'he started reading' joined by 'and.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice A is correct because it places the comma before the coordinating conjunction 'and' in the compound sentence. The pattern is: Independent clause (Jamal finished his math) , and Independent clause (he started reading). Both parts can stand alone as sentences, so comma is needed. Choice C represents missing comma in compound/comma in wrong position, which occurs when students add comma in simple sentences with compound predicates thinking all sentences with 'and' need commas. Adding comma before 'and' in 'Jamal finished his math, and started reading' is wrong because there's one subject - this is a simple sentence with compound predicate, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Keisha practiced her spelling' and 'she still missed one word' joined by 'but.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice A is correct because it places the comma before the coordinating conjunction 'but' in the compound sentence. The pattern is: Independent clause (Keisha practiced her spelling) , but Independent clause (she still missed one word). Both parts can stand alone as sentences, so comma is needed. Choice C represents adding comma in simple sentence, which occurs when students add comma in simple sentences with compound predicates thinking all sentences with 'but' need commas. Adding comma before 'but' in 'Keisha practiced her spelling, but still missed one word' is wrong because there's one subject - this is a simple sentence with compound predicate, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Sofia can draw a poster' and 'she can write a short report' joined by 'or.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice A is correct because it places the comma before the coordinating conjunction 'or' in the compound sentence. The pattern is: Independent clause (Sofia can draw a poster) , or Independent clause (she can write a short report). Both parts can stand alone as sentences, so comma is needed. Choice D represents adding comma in simple sentence, which occurs when students add comma in simple sentences with compound predicates thinking all sentences with 'or' need commas. Adding comma before 'or' in 'Sofia can draw a poster, or write a short report' is wrong because there's one subject - this is a simple sentence with compound predicate, not a compound sentence. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.

This question tests CCSS.L.4.2.c: using a comma before a coordinating conjunction in a compound sentence. Students must recognize compound sentences (two independent clauses joined by and/but/or/so) and place commas correctly. A compound sentence has two independent clauses (complete sentences) joined by a coordinating conjunction (FANBOYS: For, And, Nor, But, Or, Yet, So - focus on and, but, or, so for 4th grade). The rule is: use a comma BEFORE the coordinating conjunction when joining two independent clauses. Pattern: [Independent clause] , [conjunction] [independent clause]. Example: 'I love reading, and my sister loves math.' Both parts can stand alone as sentences ('I love reading' / 'my sister loves math'), so comma is needed before 'and.' DO NOT use comma in simple sentences with compound parts: 'I ran and jumped' (one subject, two verbs - no comma needed). In this sentence, there are two independent clauses: 'Jamal packed his lunch' and 'he hurried outside,' joined by 'and.' The first independent clause is 'Jamal packed his lunch' and the second independent clause is 'he hurried outside' joined by 'and.' Since both parts can stand alone as complete sentences, this is a compound sentence that needs a comma before the conjunction. Choice A is correct because it places the comma before the coordinating conjunction 'and' in the compound sentence. The pattern is: Independent clause (Jamal packed his lunch) , and Independent clause (he hurried outside). Both parts can stand alone as sentences, so comma is needed. Choice B represents comma in wrong position, which occurs when students put comma after conjunction instead of before. The comma must come BEFORE the conjunction, not after. To help students: Teach the 'independence test' - cover up one side of the conjunction. If the words before the conjunction can stand alone as a complete sentence AND the words after can stand alone as a complete sentence, it's compound and needs a comma before the conjunction. Practice identifying: (1) Find the conjunction (and, but, or, so). (2) Test both sides - can each stand alone? (3) If YES to both → compound → USE COMMA before conjunction. If NO → simple sentence → NO COMMA. Common example: 'I ran home and ate dinner' - Test: 'I ran home' ✓ complete, but 'ate dinner' ✗ not complete (no subject), so this is simple sentence with compound predicate (one subject, two verbs) - NO COMMA. 'I ran home, and I ate dinner' - Test: 'I ran home' ✓ complete, 'I ate dinner' ✓ complete, so compound sentence - USE COMMA. Watch for: forgetting comma in compound sentences ('I ran fast and I won the race' needs comma), adding comma in simple sentences with compound parts ('I ran, and jumped' should not have comma - one subject), confusing compound subject/predicate with compound sentence (compound sentence has two complete thoughts, not just two subjects or two verbs), putting comma after conjunction instead of before. Create practice by having students identify independent clauses before adding punctuation.