Relative clauses are one of the most reliable ways to write more complex, academically sophisticated sentences. Correct use of who/which/that/whose/where separates Band 6 from Band 7 grammar — especially when you use non-defining clauses with commas.
Defining vs Non-Defining Relative Clauses
Defining Relative Clauses
Identify which person or thing you're talking about. No commas. Cannot be removed without changing the meaning.
Example: "Students who study consistently tend to achieve higher scores." (Remove the clause and you don't know which students.)
Use: that, who, which, where, whose, when
Non-Defining Relative Clauses
Add extra information about a noun that's already clearly identified. Commas required. Can be removed without changing the core meaning.
Example: "The report, which was published in 2023, demonstrated a significant rise in renewable energy adoption."
Use: who, which, whose, where — never "that" in non-defining clauses
IELTS Writing Examples
- "Countries that invest heavily in education tend to experience stronger economic growth." (defining)
- "Technology, which has transformed almost every aspect of modern life, continues to reshape the way people communicate." (non-defining)
- "The government should target those whose income falls below the poverty line." (defining, "whose")
Common Mistakes
- Using "that" in non-defining clauses: ❌ "The policy, that was introduced last year..." → ✓ "The policy, which was introduced last year..."
- Missing commas in non-defining clauses — examiners notice this.
- Using "which" when "who" is needed for people: ❌ "scientists which discovered..." → ✓ "scientists who discovered..."
Building Complex Sentences
Combine relative clauses with other structures for maximum impact: "The economic model, which has been widely adopted across Southeast Asia, relies on export-led growth that tends to benefit urban populations more than rural communities." Two relative clauses, one sentence — this is Band 7+ grammar.
Related Guides
→ Conditionals · Articles: a/an/the · Coherence and cohesion