What is a Complex Sentence?

A complex sentence is a sentence that contains an independent clause and one or more dependent clauses. An independent clause can stand alone as a sentence, but a dependent clause even though it has a subject and a verb cannot stand alone.

Here are some examples of complex sentences. The independent clause is in bold;

All you needed? Let's practice!

Complex Sentences Explained

As you may have noticed from the examples above, a complex sentence can either start with the independent clause or the subordinate clause. If the subordinate clause comes first, you must add a comma. This is not needed if the independent clause comes first.

An independent clause contains a subject and a verb, it can stand alone as a complete thought.

The football match was cancelled.

A subordinate clause cannot stand alone, it needs to be linked to the independent clause to make sense.

Because it was raining.

Put the two together and you have a complex sentence. Often the sentence will make sense whether the independent clause or the subordinate clause is put first;

Because it was raining, the football match was cancelled.

The football match was cancelled, because it was raining.

The difference between a compound sentence and a complex sentence.

Everyone can get confused between a compound sentence and a complex sentence, so here's an easy explanation:

A compound sentence has two independent clauses. Each of these clauses is equally important, they are joined by a co-ordinating conjunction that does not change the rank of either clause. For example;

He sang and she danced.

Subject / verb / co-ordinating conjunction / subject / verb.

There are seven coordinating conjunctions that enable two clauses to be equal and they are worth taking the time to memorise;

subordinating conjunction examples

A complex sentence has one independent clause and at least one dependent clause. This means that the clauses are not equal, they use a co-ordinating conjunction that changes the rank of one or more of the clauses to make it less equal. For example;

My Dad laughed when I told a joke.

Independent clause / subordinating conjunction / dependent clause

If we took away the 'when', we would have two equal clauses; ‘My Dad laughed’ and ‘I told a joke.’ The use of the conjunction 'when' connects the clauses but displays a complex relationship between the two; indicating which is dominant and which is subordinate. Thus, a complex sentence.

There are lots of subordinating conjunctions (too many to memorise in fact!), but here are a few common examples;

Sunbordinate Conjunctions examples

Worksheets and Practice

Ready to practice sentence composition? We have a great selection of worksheets from KS1 right through to the end of KS4 on EdPlace, but check out the worksheets below to get started.

Year 1 – Joining words and clauses 1, 2 and 3.

Year 3 – Sentence composition: main and subordinate clauses.

Year 4 – Sentence composition: single and multi-clauses.

Year 5 – Sentence structure: commas and subordinate clauses 1 and 2.

Year 7 – Revise the structure of complex sentences.

Year 7 – Revise your semi-colons: joining clauses and sentences.

The BBC has a great factsheet and game on complex sentences:

http://www.bbc.co.uk/skillswise/factsheet/en28conn-l1-f-complex-sentences

http://www.bbc.co.uk/skillswise/game/en28conn-game-is-this-a-compound-sentence