Quick Summary
- Introductory clauses are dependent clauses that appear before the main clause and are always followed by a comma. The comma separates the introductory clause from the subject of the main clause.
- The most tested introductory clause rule on the SAT: the subject immediately after the comma must logically be the one performing the action in the introductory clause. When this rule is violated, it creates a dangling modifier — a very common SAT grammar trap.
- Three types of introductory elements all require commas: introductory clauses (beginning with subordinating words like "when," "although," "because"), introductory participial phrases (beginning with a verb form like "Running" or "Having finished"), and introductory prepositional phrases of four or more words.
Learn this skill with Mr. O, free
Video: Order Decides the Comma. From the Mr. O series Joining an Incomplete Clause to a Complete Sentence.
Study the full Joining an Incomplete Clause lesson (free) Practice this skill (free)
Question banks: October 2026 English question bank
Notes and practice need a free account: one click with Google, and you land straight on the lesson.
Unlocking the Secrets of Introductory Clauses: A Grammar Guide for Test Success: What This Question Tests
This example helps you practice Unlocking the Secrets of Introductory Clauses: A Grammar Guide for Test Success. It shows how to match the sentence structure to the reasoning behind each answer option. Before selecting an answer, identify the grammar rule being tested, look for signal words in the sentence, and understand why the correct choice outperforms the distractors.
Intermediate Grammar and Punctuation: Mastering Introductory Clauses
Getting introductory clauses right can improve your grammar performance on tests like the Digital SAT, EST, and ACT. This guide explains the rules in a simple, memorable format. Think of it as your tool for Unlocking the Secrets of Introductory Clauses: A Grammar Guide for Test Success.
Why Introductory Clauses Matter on Test Day
On the Digital SAT and ACT, punctuation questions appear in almost every module. The College Board's official test specifications show that Standard English Conventions questions, including comma rules for introductory elements, represent a large portion of the Writing and Language section. Getting this single rule right can earn you points that separate a good score from a great one. When you practice with official Bluebook tests, notice how often introductory clauses appear. The pattern stays the same: a dependent clause or phrase at the start of a sentence, then a comma, then the main clause.
Understanding Introductory Clauses
Introductory clauses appear at the beginning of a sentence and set up the main idea. They act like the opening act of a concert: important, but not the main event. Three types exist:
1. Subordinate Clauses
- Start with words like although, though, since, after, and others.
- Example: "Although it was raining, we decided to go hiking."
- Example: "Since we met, life has been an adventure."
- Example: "After the movie ended, we went for ice cream."
2. Prepositional Phrases
- Begin with prepositions like in, on, of, for, to, and others.
- Example: "In the midst of chaos, she found peace."
- Example: "On a sunny day, the park is full of life."
- Example: "For many people, morning coffee is essential."
3. Participle Phrases
- Start with -ing or -ed phrases.
- Example: "Running through the fields, the children laughed joyously."
- Example: "Exhausted from work, he collapsed on the sofa."
- Example: "Basking in the sun, the cat looked content."
Key Rules to Remember
- Dependent Ideas: Even though they may contain a subject and verb, introductory clauses cannot stand alone.
- Position: They always appear at the start of a sentence.
- Comma Usage: A comma must follow these clauses.
Today's Focus
- Punctuation
- Sentence Formulas
- Common Errors
A. Punctuation
An introductory clause is a dependent idea and needs punctuation to separate it from the independent clause.
- Rule: Always use a comma after the introductory clause.
- Why: It clearly separates the dependent idea from the rest of the sentence.
Examples and Analysis
- Correct: "Since the beginning of time, man, still in the primitive stages, utilized fire."
- The comma after 'time' is essential. It separates the introductory clause from the main idea.
- The phrase 'still in the primitive stages' is a non-essential clause, so commas surround it.
- Incorrect: "Since the beginning of time man, still in the primitive stages, utilized fire."
- Missing comma after 'time' creates a run-on sentence.
- Correct: "In 1887, a war broke out between the two factions, leading to chaos of a nation."
- The comma after '1887' correctly separates the introductory prepositional phrase.
- Incorrect: "In 1887 a war broke out between the two factions, leading to chaos of a nation."
- Missing comma after '1887' creates a run-on sentence.
- Correct: "Playing with his sister, Mohammed, a bright student of about 16 years old, had the perfect set to win."
- The comma after 'sister' separates the participle phrase from the rest of the sentence.
- Incorrect: "Playing with his sister Mohammed, a bright student of about 16 years old, had the perfect set to win."
- Missing comma after 'sister' causes confusion and a run-on sentence.
B. Sentence Formulas
Using formulas can help you remember where to place commas.
- Subordinating Clauses: [Subordinating] [COMMA] [Subject] [Verb]
- Example: "Although she was late, she made an impressive entrance."
- Example: "Since the store was closed, we decided to shop online."
- Prepositional Phrases: [Prepositional Phrase] [COMMA] [Subject] [Verb]
- Example: "In the heart of the city, the museum stood majestically."
- Example: "On a clear night, you can see the stars twinkling."
- Participle Phrases: [ING/ED] [COMMA] [SUBJECT] [VERB]
- Example: "Running swiftly, the athlete broke the record."
- Example: "Exhausted by the journey, they rested under the tree."
C. Common Errors
Knowing common errors is as important as knowing the rules. Here are examples to show these mistakes.
1. Run-On Sentences
A run-on sentence happens when two or more independent clauses connect improperly. One common type occurs when an introductory clause lacks a comma.
- Incorrect: "While I was walking to the store I saw an old friend from high school."
- Why It's Wrong: No comma follows the introductory clause 'While I was walking to the store'.
- Corrected: "While I was walking to the store, I saw an old friend from high school."
- Incorrect: "After the meeting ended everyone went out for dinner."
- Why It's Wrong: The introductory clause 'After the meeting ended' needs a comma after it.
- Corrected: "After the meeting ended, everyone went out for dinner."
2. Misidentification of Introductory Clauses
Sometimes sentences get punctuated wrong because the introductory clause goes unrecognized.
- Incorrect: "Despite the rain we decided to continue the match."
- Why It's Wrong: 'Despite the rain' is an introductory clause that was not identified.
- Corrected: "Despite the rain, we decided to continue the match."
- Incorrect: "Before the concert starts let's grab a bite."
- Why It's Wrong: The introductory clause 'Before the concert starts' was not identified, causing a missing comma.
- Corrected: "Before the concert starts, let's grab a bite."
3. Overuse of Commas
Using too many commas, especially within introductory clauses, can make a sentence choppy and hard to read.
- Incorrect: "In the early morning, before the sun rises, the city has a unique beauty."
- Why It's Wrong: The comma after 'morning' is unnecessary and breaks the flow.
- Corrected: "In the early morning before the sun rises, the city has a unique beauty."
- Incorrect: "After the long and tiring journey, we finally, reached our destination."
- Why It's Wrong: The comma after 'finally' is extra and not needed.
- Corrected: "After the long and tiring journey, we finally reached our destination."
How to Practice for Test Day
The best way to lock in this rule is to practice with actual test materials. Use the official Bluebook practice tests from College Board to see how introductory clause questions appear in the Digital SAT format. As you work through each passage, circle every introductory clause you find. Check that a comma follows it. Over time, this check becomes automatic. The Test Advantage recommends a simple drill: take any paragraph from a practice test, rewrite each sentence that starts with an introductory element, and remove the comma. Then go back and add the comma in the correct spot. This active recall builds speed and accuracy.
Common Mistakes Students Make
Students often confuse introductory clauses with other sentence elements. A frequent error is treating a short prepositional phrase as if it does not need a comma. On the Digital SAT, even short phrases like "In 2020" require a comma when they introduce the sentence. Another mistake is adding a comma after the subject of the main clause, thinking it belongs to the introductory element. For example, writing "After the storm, the trees, were covered in ice" is wrong. The comma after "trees" separates the subject from the verb. Stick to the formula: introductory element, comma, then the full main clause without extra commas breaking the subject-verb connection.
How to Apply This Rule Under Time Pressure
On test day, you have about 35 seconds per question in the Writing and Language section. That is not enough time to analyze every sentence from scratch. Train yourself to scan the first few words of each sentence. If you see a subordinating conjunction, a preposition, or a participle, your brain should flag it. Ask yourself: does a comma follow this opening element? If not, the answer choice is wrong. This split-second recognition is what separates students who finish on time from those who rush through the last few questions. The Test Advantage recommends timed drills using official College Board materials to build this reflex.
Why This Skill Appears Across Multiple Test Sections
Introductory clause punctuation is not limited to the Writing and Language section. On the Digital SAT Reading and Writing section, you will see questions that test your ability to edit sentences within passages. The EST and ACT also include these questions in their English and Writing sections. Beyond the test, college professors expect you to use commas correctly in essays and research papers. Mastering this rule now saves you from losing points on multiple fronts. It is a high-yield skill that pays dividends throughout your academic career.
Final Tips
- Automatic Punctuation: Think of these formulas as your grammar autopilot. When you spot an introductory clause, your mind should automatically check for the comma.
- Identification is Key: Recognizing the type of introductory clause helps in applying the correct punctuation.
- Scan the First Few Words: On test day, read the first three to five words of each sentence. If they form a dependent clause or phrase, you know a comma is coming. This scanning technique saves time and prevents careless errors.
Practice makes perfect. Try identifying introductory clauses in your reading and see if they follow these rules. Happy learning, and here is to acing those tests.
Master Comprehensive Topic Guide Index
References and Further Reading
- Official SAT Suite - What Is on the SATSupports: On the Digital SAT and ACT, punctuation questions appear in almost every module.- Official Test Publisher: Official College Board source directly verifies the claim about Digital SAT and ACT punctuation question frequency in test modules.
- National Center for Education StatisticsSupports: The College Board's official test specifications show that Standard English Conventions questions, including comma rules for introductory elements, represent a large portion of the Writing and Language section.- Official Test Publisher: Authoritative government education database provides context for test specifications and score impact claims, supporting the reference to official test specifications.
- Institute of Education SciencesSupports: Getting this single rule right can earn you points that separate a good score from a great one.- Government Database: U.S. Department of Education research institute offers evidence-based data on test score differences and percentiles, supporting the claim about point impact on scores.
Frequently Asked Questions
What is an introductory clause and how does punctuation work?
An introductory clause is a dependent clause that comes before the main clause of a sentence. It cannot stand alone as a complete sentence. After an introductory clause, place a comma before the main clause begins. Example: "When the experiment ended, the researchers reviewed the data." "When the experiment ended" is the introductory clause; the comma separates it from the main clause "the researchers reviewed the data."
What is a dangling modifier and how do I spot it on the SAT?
A dangling modifier is an introductory phrase that does not logically connect to the subject that follows the comma. Example: "Running to the store, the rain began." The subject after the comma is "the rain" — but rain cannot run to a store. The intended subject (a person) is missing. The SAT tests this by placing the wrong noun immediately after the comma. Fix: make the true performer of the introductory action the subject of the main clause: "Running to the store, she got caught in the rain."
Do all introductory elements require a comma on the SAT?
The SAT consistently tests that introductory clauses and introductory participial phrases require a comma. Short introductory prepositional phrases (one to three words like "In 2020" or "At noon") may or may not take a comma — the SAT does not test this edge case. The clear rule is: any introductory element that contains a verb form (whether conjugated or participial) always requires a comma before the main clause.
You need EST-style questions to nail introductory clauses. Get a full EST English section free, no card needed.
Start 1-day free trial →See which question types are costing you points
Start with a free mock, free drills, or preview sample questions before using all 45 question banks.
Frequently Asked Questions
What is an introductory clause?
An introductory clause is a dependent clause or phrase at the beginning of a sentence that sets up the main idea. It cannot stand alone and must be followed by a comma.
What are the three types of introductory clauses?
The three types are subordinate clauses (starting with although, since, after), prepositional phrases (starting with in, on, of), and participle phrases (starting with -ing or -ed words).
Do you always put a comma after an introductory clause?
Yes, always use a comma after an introductory clause to separate the dependent idea from the independent clause.
What is an example of a correct introductory clause sentence?
Correct: 'Since the beginning of time, man, still in the primitive stages, utilized fire.' The comma after 'time' separates the introductory clause.
What is a common error with introductory clauses?
A common error is omitting the comma after the introductory clause, which creates a run-on sentence, e.g., 'Since the beginning of time man, still in the primitive stages, utilized fire.'
What is the sentence formula for a subordinate clause?
The formula is: [Subordinating] [COMMA] [Subject] [Verb]. Example: 'Although she was late, she made an impressive entrance.'
What is the sentence formula for a prepositional phrase?
The formula is: [Prepositional Phrase] [COMMA] [Subject] [Verb]. Example: 'In the heart of the city, the museum stood majestically.'
What is the sentence formula for a participle phrase?
The formula is: [ING/ED] [COMMA] [SUBJECT] [VERB]. Example: 'Running swiftly, the athlete broke the record.'