Ever look at a Band 9 essay and wonder, “How do they make it sound so… sophisticated?”

It’s not magic. And it’s definitely not about swallowing a dictionary. Often, the secret ingredient is grammar—specifically, how you connect your ideas. That’s where relative clauses come in.

I remember a student of mine, Maria. She had great vocabulary, but her writing felt “choppy.” Short sentence after short sentence. It sounded a bit robotic. We spent one session focusing just on relative clauses, helping her combine those short sentences into longer, flowing complex sentences. Her writing score jumped from a 6.0 to a 7.0 in her next practice test. Just like that.

If you want that same boost, stick around. I’m going to break down relative clauses in a way that actually makes sense—no heavy textbook jargon, I promise.

What Exactly is a Relative Clause?

Think of a relative clause as a “describing bridge.” It connects a noun to more information about that noun, without starting a whole new sentence.

Instead of saying:

The man is my teacher. He is wearing a blue shirt.

You use a relative clause to bridge them:

The man who is wearing a blue shirt is my teacher.

See? Smoother, more efficient, and definitely more “academic.” In IELTS, this shows the examiner you can handle complex sentences, which is a key requirement for Band 7 and above.

The Two Types: Defining vs. Non-Defining

This is where most students get tripped up. But it’s actually pretty simple if you think about it in terms of “essential” vs. “extra” information.

1. Defining Relative Clauses (The Essential Ones)

These clauses give you information you need to understand which person or thing we are talking about. Without it, the sentence doesn’t make full sense.

• Example: People who exercise regularly tend to live longer.

If I just said “People tend to live longer,” you’d ask, “Which people?” The clause defines the group. Notice: NO commas.

2. Non-Defining Relative Clauses (The Extra Detail)

These clauses just give interesting extra details. You could remove the clause, and the main sentence would still be true and clear.

• Example: My brother, who lives in London, is an architect.

If I remove the clause, I’m left with “My brother is an architect.” Still makes sense, right? Because it’s extra info, we use commas like parentheses to separate it.

Examiner Tip: Missing commas in non-defining clauses is a classic Band 6 mistake. Watch out for it!

Choose Your Weapon: Relative Pronouns

Here’s a quick cheat sheet on which word to use when:

Quick note on “That”: You can use “that” instead of “who” or “which” in defining clauses, but never in non-defining ones (the ones with commas). You can’t say: “My mum, that is a cook…” – keeps it to “who”!

How to Use This in Your Exam

In Writing Task 1

Relative clauses are perfect for describing data without sounding repetitive.

• “The graph shows the percentage of people who use the internet.”
• “France, which had the highest number of tourists, saw a steady increase.”

For more on this, check out our guide on Academic Task 1 writing.

In Writing Task 2

Use them to expand your arguments and definitions.

• “Employees who feel valued by their bosses are often more productive.”
• “Global warming, which is a pressing issue today, requires immediate action.”

In Speaking

Don’t just give one-word answers! Use relative clauses to extend your speech in Part 3.

Examiner: “What kind of gifts do people like?”
You: “Well, I think most people prefer gifts that are thoughtful and personal, rather than just expensive.”

Common Traps to Avoid

I see these mistakes all the time. Don’t be that student!

1. The Double Subject:
   Incorrect: The man who he called me was angry.
   Correct: The man who called me was angry. (The relative pronoun IS the subject!)
2. Wrong Pronoun for People:
   Incorrect: The teacher which taught me…
   Correct: The teacher who taught me…
3. Comma Chaos:
   Remember: Essential info = NO commas. Extra info = YES commas.

Let’s Practise

Try combining these sentences yourself (answers at the bottom!):

1. The phone is on the table. It is broken.
2. My sister is a doctor. She lives in Australia.

(Scroll down for answers…)

…

Answers:
1. The phone which/that is on the table is broken.
2. My sister, who lives in Australia, is a doctor.

Final Thoughts

Relative clauses might seem like a small detail, but they are powerful tools for building the complex sentence structures you need for a high score. Start by noticing them when you read English articles (like on the BBC Learning English site) and try adding just one or two into your next practice essay.

You’ve got this! If you need more help with grammar, check out our list of the best IELTS grammar books.