Difficulty: Foundational | Prerequisites: Parts of Speech, Verbs, and Agreement notes
This cluster covers how sentences are built from phrases and clauses, how conjunctions join them, and the most common sentence-level errors: fragments, run-ons, comma splices, misplaced and dangling modifiers, and faulty parallelism. Mastering these topics is the bridge between knowing grammar rules and writing clear, correct prose. If you are comfortable with parts of speech and subject-verb agreement, you are ready for this material.
Sentences are built from phrases and clauses. Independent clauses stand alone; dependent clauses cannot. Coordinating conjunctions (FANBOYS) join independent clauses into compound sentences; subordinating conjunctions create complex sentences. The most common errors at this level are fragments (incomplete sentences), run-ons and comma splices (improperly joined clauses), misplaced or dangling modifiers, and faulty parallelism.
Phrase
A small series of words that conveys some meaning but does not require a subject and verb.
Think of it as a fragment of information that needs a full sentence to make sense: "in the morning," "without knowing why."
Clause
A group of words that includes a subject and a verb.
Independent clause
A group of words that can stand alone as a sentence. It has a subject, a verb, and a complete thought.
In simple terms, if it works on its own, it is independent.
Dependent clause
A clause that cannot stand on its own as a sentence because it is missing a complete thought.
It still has a subject and verb but relies on an independent clause to make sense: "While he was tired" leaves you wanting more.
Conjunction
A word or phrase that connects parts of a sentence.
Coordinating conjunction
A conjunction that connects two independent clauses into a compound sentence. Remembered by the acronym FANBOYS: For, And, Nor, But, Or, Yet, So.
Subordinating conjunction
A word or phrase that connects an independent clause to a dependent clause: after, although, because, when, while, until, since, if.
Compound sentence
A sentence that contains two or more independent clauses, joined by a coordinating conjunction and a comma.
Complex sentence
A sentence that combines at least one dependent clause with at least one independent clause, joined by a subordinating conjunction.
Comma
A punctuation symbol used to indicate a pause or a particular organisation: in lists, compound and complex sentences, introductory phrases, and around interruptions.
Comma splice
A grammatically incorrect sentence in which a comma separates two independent clauses without a coordinating conjunction.
In simple terms, a comma alone cannot glue two full sentences together.
Sentence fragment
A phrase or clause that does not meet all the criteria of a sentence (missing a subject, a verb, or a complete thought).
Run-on sentence
A sentence that includes multiple independent clauses not connected correctly, either lacking punctuation or a proper conjunction.
Modifier
A word, phrase, or clause that provides more information about something in the sentence.
Misplaced modifier
A modifier that is separated from the thing it modifies, creating confusion or unintended meaning.
"The coat that I tried on was too big in the store" makes it sound like the coat was only big inside the store.
Dangling modifier
A modifier that modifies something not clearly identified in the sentence.
"Thirsty, the milk was gone in minutes" accidentally suggests the milk was thirsty.
Parallelism
The use of repeating grammatical structures to emphasise similarities between ideas.
In simple terms, items in a list or comparison should match in form: "to sing, to dance, and to swim," not "singing, to dance, and to swim."
A phrase is a small chunk of meaning without a subject-verb pair: "in the morning," "without knowing why." The most common type is the prepositional phrase. Phrases add detail to sentences but cannot stand alone.
A clause always contains a subject and a verb. There are two kinds: independent (can stand alone) and dependent (cannot).
Independent clause: subject + verb + complete thought. "The dog sat in the doghouse." This is also called a simple sentence.
Dependent clause: has a subject and verb but is missing a complete thought. "While he was tired" needs more information. Dependent clauses often begin with a subordinating conjunction (while, because, after, if, since).
A coordinating conjunction connects two independent clauses into a compound sentence. Remember them with FANBOYS:
For = because (cause-effect)
And = adds more information
Nor = negation
But = contradiction
Or = offers options
Yet = similar to but (contradiction)
So = result/effect
In a compound sentence, always place a comma before the coordinating conjunction: "I want to pet that dog, but he has fleas."
When a coordinating conjunction connects two words rather than two clauses, no comma is needed: "I could pet a dog or cat."
A subordinating conjunction connects a dependent clause to an independent clause, creating a complex sentence.
Common subordinating conjunctions: after, although, because, before, if, since, until, when, where, while.
Comma rule for complex sentences:
Dependent clause first, comma required: "Since I brought my presents, I am ready for the holidays."
Independent clause first, no comma: "I am ready for the holidays since I brought my presents."
Commas separate and organise relationships between words and phrases. Key situations:
Lists: commas between each item in a series of three or more, including before the final "and" or "or." "Nashville, Atlanta, and New Orleans."
Compound sentences: comma before the coordinating conjunction. "The day is cold, but it's not snowing."
Complex sentences (dependent clause first): comma after the dependent clause. "Since it's not snowing, we can't go skiing."
Introductory phrases: comma after an introductory phrase. "On snowy days, it's common for many people to work from home."
Interruptions: commas surround interruptive phrases. "My family, none of whom have ever skied before, are planning a trip."
Dialogue: commas set off quoted speech. '"I can't wait," said my sister.'
Dates and places: "January 1, 2016" and "Seattle, Washington."
If you are unsure whether a comma belongs, read the sentence aloud and listen for natural pauses.
A fragment is missing one or more of the three essential ingredients: subject, verb, or complete thought.
To identify a fragment, ask three questions:
Does this sentence have a subject?
Does this sentence have a verb?
Does this sentence form a complete thought?
Quick test: add "It is true that" to the beginning. If the result makes sense, the sentence is complete. If not, it is a fragment.
To fix a fragment: add the missing subject or verb, or attach the dependent clause to a nearby independent clause. If the fragment starts with a subordinating conjunction like "because," either remove the conjunction or connect it to an independent clause.
A run-on has multiple independent clauses without correct punctuation or conjunctions.
Two main types:
Comma splice: two independent clauses joined by only a comma, missing the coordinating conjunction. "Today is my birthday, all my friends are coming" is a comma splice.
Missing punctuation entirely: "All of my friends are coming to dinner and we are having cake" is a run-on because the coordinating conjunction "and" lacks a comma.
Four ways to fix a run-on:
Split into two separate sentences.
Add a comma and a coordinating conjunction.
Use a semicolon between the clauses.
Add a subordinating conjunction to make one clause dependent.
To avoid run-ons while writing: keep sentences to two clauses or fewer, and if you cannot remember how a sentence started, it is probably too long.
Modifiers should sit as close as possible to the word they modify.
Misplaced modifier: the modifier is in the wrong spot and accidentally modifies the wrong word. "I'll serve coffee to my guests in big red mugs" sounds like the guests are inside the mugs. Fix: "I'll serve coffee in big red mugs to my guests."
Even single words matter. "I just sold my muffins" (moments ago) means something different from "I sold just my muffins" (only the muffins, nothing else).
Dangling modifier: the modifier has nothing to attach to. "Thirsty, the milk was gone in minutes" gives the milk a thirst. Fix by adding the missing subject: "Thirsty, the children drank up all the milk in minutes."
Items in a list or comparison must match in grammatical form.
Correct: "I like to sing, to dance, and to swim."
Incorrect: "I like singing, to dance, and to swim." ("singing" breaks the infinitive pattern.)
Correct: "The dungeon was cold, damp, and uncomfortable."
Incorrect: "The dungeon was cold, damp, and it was uncomfortable." (The third item switches structure.)
For lists with prepositions, repeat the preposition consistently: "I wanted to travel in Spain, in Italy, and in Portugal."
Students often think any long sentence is a run-on. Length alone does not make a run-on. A run-on is specifically about missing punctuation or conjunctions between independent clauses, not about word count.
Students think a comma can always join two sentences. It cannot. A comma between two independent clauses without a coordinating conjunction creates a comma splice. You need a conjunction, a semicolon, or a full stop.
Students place modifiers far from the word they describe and do not realise the sentence now says something unintended. Always re-read to check what the modifier is actually modifying.
Students confuse dependent clauses with fragments. A dependent clause has a subject and verb, so it looks complete, but the subordinating conjunction at the start ("because," "when") means it cannot stand alone.
⚠️ The FANBOYS acronym (For, And, Nor, But, Or, Yet, So) is almost certainly on any grammar exam. Know all seven and what each one signals.
⚠️ Comma placement in compound vs. complex sentences: comma before the conjunction in compound sentences, comma after the dependent clause in complex sentences (when it comes first).
⚠️ Distinguishing fragments from complete sentences using the three-question test (subject? verb? complete thought?) is a staple exam question.
⚠️ Identifying and fixing comma splices and run-ons: expect questions asking you to choose the correct fix (split, add conjunction, semicolon, or subordinating conjunction).
⚠️ Parallelism errors in lists: exam questions often present a list with one mismatched item and ask you to correct it.
True or false: "Because she was tired" is a complete sentence. (False. It is a dependent clause, a fragment.)
What does the acronym FANBOYS stand for? (For, And, Nor, But, Or, Yet, So.)
True or false: In a compound sentence, the comma goes after the coordinating conjunction. (False. The comma goes before the coordinating conjunction.)
Fill in the blank: A ____ ____ is a sentence error where a comma alone separates two independent clauses. (Comma splice.)
True or false: "Running quickly, the finish line was crossed" contains a dangling modifier. (True. Who is running? The finish line cannot run. The subject is missing.)
Q: What is the difference between a phrase and a clause?
A: A phrase is a small group of words that conveys meaning but does not include a subject-verb pair ("in the morning"). A clause includes both a subject and a verb ("while he was tired").
Q: Identify and correct the comma splice: "Today is my birthday, all my friends are coming for dinner."
A: This is a comma splice because two independent clauses are joined by only a comma. Fix: "Today is my birthday, so all my friends are coming for dinner" (add coordinating conjunction), or "Today is my birthday; all my friends are coming for dinner" (use semicolon).
Q: Fix the parallelism error: "I like singing, to dance, and to swim."
A: The items are not in the same grammatical form. Corrected: "I like singing, dancing, and swimming" or "I like to sing, to dance, and to swim."
Q: Fix the dangling modifier: "Thirsty, the milk was gone in minutes."
A: The modifier "thirsty" has no clear subject. Corrected: "Thirsty, the children drank all the milk in minutes."
Q: Is this a fragment, a run-on, or a correct sentence? "Wanted to cross the bridge."
A: Fragment. It is missing a subject. Who wanted to cross the bridge? Corrected: "She wanted to cross the bridge."
Q: Where does the comma go in a complex sentence where the dependent clause comes first?
A: After the dependent clause, before the independent clause begins. "Since it's not snowing, we can't go skiing."
Understanding clauses and conjunctions is essential for Paragraph Development, because well-constructed paragraphs depend on varied sentence types (simple, compound, complex). Comma rules carry into every piece of writing you do. Parallelism becomes especially important when writing TEE paragraphs and academic arguments, where lists of evidence must be grammatically consistent.
Phrase, clause, independent clause, dependent clause, simple sentence, compound sentence, complex sentence, conjunction, coordinating conjunction, subordinating conjunction, FANBOYS, comma, comma splice, introductory phrase, sentence fragment, run-on sentence, semicolon, modifier, misplaced modifier, dangling modifier, parallelism, parallel structure, ENG 18, Foundations of English Composition, Sophia Pathways, sentence errors, sentence construction, grammar, punctuation