What is a subordinate clause? In KS3 English, it is a group of words containing a subject and a verb that cannot stand alone as a complete sentence, because it depends on a main clause for its meaning. Subordinate clauses add extra detail, condition, time, reason, or contrast to a sentence.
What is the difference between a main clause and a subordinate clause?
A main clause (also called an independent clause) contains a subject and a verb and expresses a complete thought — it can stand alone as a sentence. "The tide was rising fast" is a main clause; it makes sense by itself.
A subordinate clause also contains a subject and a verb, but it cannot stand alone, because a subordinating word at its start makes it dependent on the rest of the sentence. "Because the tide was rising fast" contains a subject ("tide") and a verb ("was rising"), but the word "Because" makes it incomplete — the reader is left waiting for the consequence.
Every complex sentence needs at least one of each: a main clause that can survive alone, and a subordinate clause that cannot.
What are subordinating conjunctions?
Subordinating conjunctions are the words that turn a clause into a subordinate clause by making it dependent on a main clause. Each one signals a particular kind of relationship between the two clauses.
| Subordinating conjunction | Relationship signalled | Example |
|---|---|---|
| because, since, as | Reason | "She left early because the film had finished." |
| although, though, even though | Contrast | "Although he was tired, he kept running." |
| when, while, after, before | Time | "The dog barked when the doorbell rang." |
| if, unless | Condition | "You will fail unless you revise." |
| so that | Purpose | "She whispered so that no one would hear." |
Once you can spot one of these words at the start of a clause, you have almost certainly found a subordinate clause.
Where can a subordinate clause go in a sentence?
A subordinate clause can appear before, after, or in the middle of the main clause, and its position changes the punctuation required.
Subordinate clause first (fronted): "Because the tide was rising fast, the children ran back up the beach." A comma is needed after the subordinate clause when it opens the sentence.
Subordinate clause last: "The children ran back up the beach because the tide was rising fast." No comma is needed when the subordinate clause follows the main clause.
Subordinate clause in the middle: "The children, because the tide was rising fast, ran back up the beach." Here the subordinate clause interrupts the main clause and needs a comma on both sides.
All three versions communicate the same information — the choice of position is a stylistic decision that changes emphasis and rhythm, not meaning.
What are relative clauses — a special type of subordinate clause?
A relative clause is a subordinate clause introduced by a relative pronoun — who, whom, whose, which, or that — that gives extra information about a noun.
"The dog, which had been barking all night, finally fell silent." The relative clause "which had been barking all night" gives extra information about "the dog" and is embedded inside the main clause, with a comma before and after because the information is not essential to identifying which dog is meant.
Compare: "The dog that bit the postman was put on a lead." Here the relative clause "that bit the postman" is essential — it identifies which specific dog — so no commas are used. This distinction (essential versus extra information) is one of the more advanced punctuation rules examiners look for at the top of the GCSE mark range.
Why do subordinate clauses matter for GCSE English?
Subordinate clauses are the building block of the complex sentence, and complex sentences are what allow writers to show relationships between ideas — cause, contrast, condition, and time — rather than simply listing facts.
- In writing, using subordinate clauses accurately, and varying their position in the sentence, is rewarded under the technical accuracy and sentence variety criteria on GCSE English Language Paper 1 and Paper 2.
- In reading and language analysis, examiners expect students to comment on how a writer uses subordination — for example, delaying the main clause to build suspense, or piling up subordinate clauses to overwhelm the reader with detail.
- In punctuation, most comma errors at GCSE come from mishandling subordinate clauses: forgetting the comma after a fronted subordinate clause, or adding unnecessary commas around an essential relative clause.
To recap what is a subordinate clause KS3 grammar teaching centres on: a dependent group of words with a subject and a verb that relies on a main clause to make complete sense.
How can you practise identifying subordinate clauses?
- Underline every subordinating conjunction (because, although, when, if, since, while, that, which, who) you can find in a paragraph.
- For each one, work out where the subordinate clause starts and ends, and check whether the remaining part of the sentence can stand alone as a main clause.
- Try moving the subordinate clause to a different position in the sentence (start, middle, end) and add the correct punctuation each time.
- Write three of your own sentences using a different subordinating conjunction in each, deliberately changing the clause's position.
Frequently asked questions
Can a subordinate clause stand alone as a sentence?
No — that is the defining feature of a subordinate clause. Even though it contains a subject and a verb, the subordinating conjunction (such as "because" or "although") makes it grammatically incomplete, so it always needs a main clause to attach to. Writing a subordinate clause on its own, such as "Because the tide was rising fast." as a full sentence, is a common error called a sentence fragment.
Do you always need a comma after a subordinate clause?
Only when the subordinate clause comes before the main clause. "Although it was raining, we went outside" needs a comma after "raining". If the order is reversed — "We went outside although it was raining" — no comma is needed, because the subordinate clause now follows the main clause.
What is the difference between a subordinate clause and a relative clause?
A relative clause is one specific type of subordinate clause, introduced by a relative pronoun (who, which, that, whose) rather than a subordinating conjunction (because, although, when). All relative clauses are subordinate clauses, but not all subordinate clauses are relative clauses — some are introduced by conjunctions that signal reason, time, or condition instead.
How many subordinate clauses can one sentence have?
There is no fixed limit — a sentence can contain several subordinate clauses alongside its main clause, though GCSE examiners tend to reward clarity over complexity. A sentence with two or three well-placed subordinate clauses that remains easy to follow is more effective than one with five that becomes tangled and hard to parse.
For Socratic English grammar practice on clauses and sentence structure, see aitutors.me.