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Simple, Compound and Complex Sentences Explained

Identify clauses and build simple, compound and complex sentences for clearer, more varied writing, with examples.

  • ⏱ 3 min read
  • ✏️ 3 worked examples
  • 🎯 5 practice questions
  • 📶 Beginner
KS3GCSEMiddle SchoolHigh School
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Curriculum fit: GCSE English Language (writing: sentence structures; spelling, punctuation and grammar). US: Common Core ELA Language standards (grades 6-10).

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What Is It?

A clause is a group of words with a subject and a verb. A main (independent) clause makes sense on its own. A subordinate (dependent) clause does not: it adds extra information and needs a main clause to complete it.

Using different sentence types makes your writing more interesting and lets you show how ideas connect.

Simpleone main clause: The dog barked.Compoundtwo main clauses joined by and, but, or, soComplexa main clause plus a subordinate clauseCompound-complextwo main clauses plus a subordinate one
Mixing sentence types makes writing more varied. A main clause makes sense on its own, and a subordinate clause does not.

Key Formulas and Ideas

  • Simple sentence: one main clause. 'The dog barked.'
  • Compound sentence: two main clauses joined by a coordinating conjunction (for, and, nor, but, or, yet, so, remembered as FANBOYS).
  • Complex sentence: a main clause plus a subordinate clause, joined by a word such as because, although, when, if or while.
  • Compound-complex: at least two main clauses and one subordinate clause.

Worked Examples

Example 1

Identify

Question

Label each sentence: (a) 'Maya laughed.' (b) 'Maya laughed, but Sam stayed silent.' (c) 'Although it was late, Maya laughed.'

  1. (a) has one main clause, so it is simple.
  2. (b) has two main clauses joined by 'but', so it is compound.
  3. (c) has a subordinate clause ('Although it was late') and a main clause, so it is complex.

✓ Answer (a) simple, (b) compound, (c) complex

Example 2

Combine

Question

Join 'The match was cancelled' and 'It rained heavily' into one complex sentence.

  1. Choose a subordinating conjunction that shows the reason: because.
  2. Write: The match was cancelled because it rained heavily.

✓ Answer The match was cancelled because it rained heavily.

Example 3

Fix a Run-on

Question

Fix: 'I was tired I went to bed.'

  1. This joins two main clauses with no punctuation or conjunction.
  2. Add a coordinating conjunction and a comma: 'I was tired, so I went to bed.'

✓ Answer I was tired, so I went to bed.

Common Mistakes to Avoid

  • Joining two main clauses with only a comma (a comma splice).
  • Leaving a subordinate clause on its own as a sentence (a fragment).
  • Using the same sentence pattern throughout a paragraph.
  • Forgetting the comma after a subordinate clause that begins a sentence.

Practice Questions

0 of 5 answered
Q1'The rain stopped.' is which type of sentence?
Q2'I wanted to go, but it rained.' is…
Q3Which is the subordinate clause in 'We stayed in because it rained'?
Q4Which is a fragment?
Q5Which conjunction is NOT a coordinating conjunction?

Frequently Asked Questions

What does FANBOYS stand for?

For, And, Nor, But, Or, Yet, So: the seven coordinating conjunctions.

Can a simple sentence be long?

Yes. 'Simple' means one main clause, not that it is short.

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Sources and Review

Reviewed by StudyMorrow editorial review on 5 Nov 2026.