Grammar: Clauses
Understand main clauses, subordinate clauses, and how they combine to create complex sentences that improve your writing.
What is a Clause?
A clause is a group of words that contains a subject (who or what) and a verb (what they do). Clauses are the building blocks of sentences. There are two types:
Main Clause (Independent)
Makes complete sense on its own. It can be a sentence by itself.
The children played in the park.
Subject: The children | Verb: played
She finished her homework.
Subject: She | Verb: finished
Subordinate Clause (Dependent)
Cannot stand alone. It needs a main clause to make sense.
because it was raining
Has a subject and verb but feels incomplete.
when the bell rang
Leaves you asking "what happened?"
Types of Subordinate Clauses
Subordinate clauses do different jobs in a sentence. Here are three common types:
Time Clause (when, while, before, after, until)
After the game finished, the players shook hands.
Tells us when something happened.
Reason Clause (because, since, as)
She wore sunscreen because the sun was strong.
Tells us why something happened.
Condition Clause (if, unless)
If you study hard, you will do well in the test.
Tells us the condition for something to happen.
The Comma Rule
When joining a main clause and a subordinate clause, the position of the comma depends on which clause comes first:
Subordinate clause FIRST = Comma needed
Because it was cold, she wore a jacket.
Main clause FIRST = No comma needed
She wore a jacket because it was cold.
Key Vocabulary
Clause
A group of words containing a subject and a verb.
Main Clause
A clause that makes complete sense on its own and can stand as a sentence.
Subordinate Clause
A clause that depends on a main clause and cannot stand alone as a sentence.
Subordinating Conjunction
A word that introduces a subordinate clause (because, when, if, although, while, until).
Worked Examples
Practise identifying and combining clauses.
Example 1: Identifying Clauses
Sentence: "While Mum cooked dinner, Dad set the table."
Subordinate clause: "While Mum cooked dinner" (starts with "while", cannot stand alone)
Main clause: "Dad set the table" (makes sense on its own)
Example 2: Combining Clauses
Simple sentences: "The dog barked loudly." + "A stranger knocked on the door."
Complex sentence: The dog barked loudly because a stranger knocked on the door.
The subordinating conjunction "because" shows the reason for the barking.
Example 3: Changing Clause Position
Version 1: We stayed inside because it was stormy. (No comma needed)
Version 2: Because it was stormy, we stayed inside. (Comma needed)
Both versions mean the same thing. Placing the subordinate clause first adds emphasis to the reason.
Knowledge Check
Test your understanding of clauses. Select the correct answer and click "Check Answer".
Question 1
What must every clause contain?
Question 2
Which of these is a subordinate clause?
Question 3
In the sentence "If you practise every day, you will improve", what type of subordinate clause is used?
Question 4
Which sentence uses a comma correctly?
Question 5
Which word is a subordinating conjunction?
Key Concepts Summary
- ● A clause is a group of words with a subject and a verb.
- ● A main clause makes sense on its own. A subordinate clause cannot stand alone.
- ● Subordinate clauses can show time (when, while), reason (because, since), or condition (if, unless).
- ● Use a comma after the subordinate clause when it comes first in the sentence.
- ● Combining clauses creates complex sentences that make your writing more interesting and detailed.