Count the main clauses: simple, compound, complex
The Short Answer
A simple sentence is one main clause. A compound sentence is two main clauses joined by and, but or or. A complex sentence is a main clause plus a subordinate clause. So the question is really counting: find the clauses, decide which are main, and the label follows. A comma on its own never makes a compound sentence.
What is a sentence type question?
Your child is given a sentence and asked whether it is simple, compound or complex.
If they can already sort clauses, this question is arithmetic. If they cannot, it is guesswork — which is why we teach clauses first and treat this as the thing that follows.
The three labels
| Label | What it contains |
|---|---|
| Simple | One main clause |
| Compound | Two main clauses joined by and, but or or |
| Complex | A main clause plus a subordinate clause |
So the method is counting. Find the clauses. Decide which could stand alone. Read off the label.
Can you show me a worked example?
A comma does not make a compound sentence
This is the trap in this family, and it appears constantly.
The tide turned, the boats swung round.
Two clauses that could each stand alone — so far so compound. But there is no joining word, only a comma, and a comma is not strong enough to hold two sentences together. That is an error, not a sentence type.
To be compound it needs and, but or or. To be correct as written it needs a semicolon or a full stop.
Where do pupils lose marks?
Judging by length. A long sentence with one clause is simple; a five-word sentence with two is compound.
Calling a comma splice compound, which is the trap above.
Stopping at the first verb and concluding there is only one clause.
Try it yourself
Find the clauses first, decide which could stand alone, then name the sentence.
- The lanterns hung above the harbour.
- Nadia repaired the engine although the storm had started.
- Bilal spoke and the hall fell silent.
- Ola practised the violin until her fingers ached, and her brother waited outside.
- The tide turned, the boats swung round.
- Simple. One clause, and it stands alone.
- Complex. 'Nadia repaired the engine' is a main clause; 'although the storm had started' cannot stand alone, so it is subordinate.
- Compound. Two clauses, each of which would work on its own, joined by and.
- Compound-complex — a main clause with a subordinate clause attached, joined by and to a second main clause. If the paper offers only three labels, this counts as complex, because the subordinate clause is the feature being asked about.
- Neither, strictly: this is two main clauses joined by nothing but a comma, which is an error rather than a sentence type. Written correctly it would be a compound sentence with 'and', or two separate sentences.
How much practice does this type need at home?
Build rather than label. Give your child a simple sentence — the lanterns hung above the harbour — and ask them to turn it into a compound one, then a complex one.
Making a complex sentence forces them to produce a subordinate clause, and producing one teaches the difference far more reliably than identifying somebody else's. It also takes about a minute, which means it can be done while the kettle boils.
Free: an English workbook
Questions across the English question types, with the method printed at the top and full answers at the back. One workbook for the whole strand, not a sheet per question type.
Frequently Asked Questions
Why does a comma not make a compound sentence?
Because a compound sentence needs a joining word — and, but, or — as well as two clauses that could each stand alone. 'The tide turned, the boats swung round' has the two clauses and no joiner, which makes it a punctuation error rather than a compound sentence. This matters because it appears in both the punctuation and the sentence type questions, wearing a different hat each time.
How does my child count the clauses quickly?
Count the verbs first, since every clause has one. Two verbs usually means two clauses. Then ask of each whether it would stand alone. That gives you the number of main clauses, and the number of main clauses is what decides the label — one is simple, two is compound, and one plus something that cannot stand alone is complex.
What if a sentence has both a joining word and a subordinate clause?
Then it is doing both things, and some papers call that compound-complex. Where only three labels are offered, choose complex — the subordinate clause is the feature the question is asking about, and it is the part that makes the sentence more than a simple join. If your child meets four labels, count properly: two main clauses and one subordinate makes compound-complex.
Is a longer sentence always more complex?
No, and it is worth saying plainly. 'The exhausted climbers rested briefly beside the icy lake after their long ascent' is one main clause with a phrase attached — a simple sentence, despite its length. Meanwhile 'I ran and he followed' is compound in five words. The label is about clauses, not about length.
Sources
- GL Assessment — 11+ familiarisation materials and question type descriptions Published 2025.
- Clever Clogs Academy — our own Year 4 and Year 5 lesson records, Winslow Published September 2025 to July 2026.
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