KS2 SATs English: Sentence Structure and Clauses Guide

Simple sentences

A simple sentence has one main clause with a subject and a verb: "The dog barked."

Compound sentences

A compound sentence joins two main clauses with a coordinating conjunction (and, but, or, so): "The dog barked and the cat ran away."

Complex sentences

A complex sentence has a main clause and at least one subordinate clause, joined by a subordinating conjunction (because, although, when, if, while): "The dog barked because a stranger walked past."

Identifying clauses

A main clause makes sense on its own. A subordinate clause doesn't make sense on its own and depends on the main clause — a useful test is to check whether the clause could stand alone as a sentence.

Common mistakes

• Mistaking a subordinate clause for a full sentence.
• Forgetting a comma is often needed when a subordinate clause starts the sentence.
• Overusing "and" to join ideas instead of varying sentence structure.