A sentence is a group of words that makes complete sense on its own and contains a subject and a verb. Knowing the four sentence functions and the three sentence structures lets you write with variety and control.
Why this matters IGCSE examiners reward "varied sentence structures used for effect". Short simple sentences create impact; longer complex sentences carry detail. If you can build each type on purpose, you can control pace and emphasis in your writing.
Four sentence functions
- Statement (declarative): gives information and ends in a full stop. Omar finished his homework.
- Question (interrogative): asks something and ends in a question mark. Have you seen my pen?
- Command (imperative): tells someone to do something. Close the window.
- Exclamation: shows strong feeling and ends in an exclamation mark. What a beautiful day!
Clauses: the building blocks
A clause has a subject and a verb. A main clause makes sense alone (Aisha smiled). A subordinate clause does not make sense alone (because she was happy).
Three sentence structures
- Simple: one main clause. Bilal scored a goal.
- Compound: two main clauses joined by a coordinating conjunction (and, but, or, so). Bilal scored a goal, and the crowd cheered.
- Complex: a main clause plus at least one subordinate clause. When the whistle blew, Bilal scored a goal.
Notice that a complex sentence can put the subordinate clause first or second. When it comes first, a comma usually follows it: When the whistle blew, Bilal scored. When it comes second, you often need no comma: Bilal scored when the whistle blew. Mixing simple, compound and complex sentences within a paragraph keeps your writing lively and easy to read.
Watch out for the run-on sentence, where two main clauses are wrongly joined with only a comma: The rain stopped, we went outside. Fix it with a conjunction, a full stop or a semicolon.
Common exam mistake: The run-on sentence — joining two main clauses with only a comma, such as "The rain stopped, we went outside." A comma alone cannot join two complete sentences; use a conjunction, a full stop or a semicolon instead.
Exam technique: Deliberately mix simple, compound and complex sentences within a paragraph rather than letting one type dominate. A short simple sentence placed after several longer ones creates real impact — plan this variety on purpose, not by accident.