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Year 3 English Grammar

Complex Sentences

A complex sentence has a main clause and a subordinate clause joined by a subordinating conjunction like "because", "when" or "although".

What You Need to Know

A complex sentence has two parts: a main clause (a complete idea that makes sense on its own) and a subordinate clause (extra information that depends on the main clause). They are joined by a subordinating conjunction like because, when, although, while, after, before, unless, since. The subordinate clause can come first or second in a sentence.

Key Concepts

Main Clause

Makes sense on its own

Subordinate Clause

Depends on the main clause

Subordinating Conjunction

because, when, although...

Comma Rule

Comma needed if clause comes first

Main clause first, subordinate clause second (no comma needed):

I stayed inside because it was raining.

Subordinate clause first, main clause second (comma needed):

Although she was tired, she kept reading.

Key Vocabulary

Main Clause

A group of words with a subject and verb that makes complete sense on its own.

Subordinate Clause

A clause that cannot stand alone — it needs the main clause to make full sense.

Subordinating Conjunction

A word that introduces a subordinate clause: because, when, although, while, after, before, since, unless.

Complex Sentence

A sentence with one main clause and at least one subordinate clause joined by a subordinating conjunction.

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

Which sentence is a complex sentence?

Question 2

Which part is the main clause in this sentence? "Although it was late, she finished her homework."

Question 3

Which word is a subordinating conjunction?

Question 4

When the subordinate clause comes first in a sentence, you need:

Key Concepts Summary