Relative Clauses: Defining, Non-defining & Practice

Relative clauses make writing more precise because they join two ideas without repeating the noun. Compare The learner asked a question. The learner sits near the door with The learner who sits near the door asked a question. The key decision is whether the clause identifies the noun or simply adds a comment.

What is a relative clause?

A relative clause follows a noun and works like an adjective: it tells us which person or thing, or gives extra information about it.

Two shorter ideas	One precise sentence
I met a designer. The designer works in Bristol.	I met a designer who works in Bristol.
We visited a museum. The museum opened in 1902.	We visited a museum that opened in 1902.
I found the notes. You sent the notes.	I found the notes which you sent.

The relative word connects the noun to the information that follows. Check its job inside the clause, not only the noun before it.

Defining relative clauses: essential information

A defining relative clause tells us exactly which person or thing we mean. Without it, the listener may not know the reference. Do not put commas around a defining clause.

• The learner who won the quiz is in my class.
• I need the file that contains the final data.
• The restaurant where we met has closed.

Use these common relative words:

Relative word	Typical reference	Example
who	people	The tutor who called left a message.
which	things and animals	The tool which saves time is free.
that	people, things and animals in defining clauses	The rule that confused me is clearer now.
whose	possession	The student whose notebook is missing is absent.
where	places	This is the room where we practise.
when	times	I remember the year when we moved.

Who, which or that?

For people, who is the normal choice. For things, use which or that. That is common in defining clauses and is often less formal than which or who when it refers to people.

• The colleague who designed the poster is here.
• The poster which won the prize is on the wall.
• The poster that won the prize is on the wall.

Do not force that into every sentence. It cannot introduce a non-defining clause, and it cannot follow a preposition directly: write the person to whom I wrote, not the person to that I wrote.

Non-defining relative clauses: extra information

A non-defining relative clause adds information about a noun that is already clear. Use commas at both ends of the clause. The sentence still identifies the noun without it.

• My brother, who lives in Leeds, is visiting on Sunday.
• The new library, which opened last month, has quiet study rooms.
• This laptop, whose battery is new, belongs to the teacher.

Use who, which or whose. Do not use that in a non-defining clause.

The clause can also comment on the whole previous idea:

The class finished early, which surprised the substitute teacher.

Here which means “the fact that the class finished early”, not one noun. Keep the comma because the clause is an additional comment.

Subject and object: when can you omit the word?

In a defining clause, the relative word can sometimes be omitted when it is the object of the verb.

Role in the clause	Example	Omit?
subject	The guide who explained the map was helpful.	No: who does the action.
object	The map (which) the guide explained was helpful.	Yes: the guide does the action.

Test the clause by asking who performs the verb. In the guide who explained, the guide explained. In the map which the guide explained, the guide explained the map, so which is an object and can disappear.

Do not leave an extra object pronoun behind:

• Correct: The book (that) I borrowed was useful.
• Incorrect: The book that I borrowed it was useful.

Whose, where and when

Use whose for possession, including possession by people, animals and sometimes things in formal writing.

• We met a researcher whose work changed the field.
• I visited a town whose station is over 100 years old.

Use where for a place and when for a time. They are often clearer than a longer preposition phrase.

• The café where we studied is still open.
• Friday was the day when the results arrived.

You can also use which with a preposition when the grammar needs it: the café in which we studied. That is more formal than the café where we studied.

Punctuation changes the meaning

Compare these sentences carefully:

• The students who completed the task received feedback. Only those students received feedback.
• The students, who completed the task, received feedback. The speaker presents completing the task as information about all the students.

Commas are not decoration. They tell the reader whether the clause is necessary to identify the noun or an aside about an already identified noun.

Seven common mistakes to correct

Incorrect	Better	Why
The woman which called is my tutor.	The woman who called is my tutor.	Use who for people.
My car, that is outside, is new.	My car, which is outside, is new.	That is not used in non-defining clauses.
The book who I borrowed was useful.	The book which/that I borrowed was useful.	Use which or that for a thing.
The student whose he won is absent.	The student who won is absent.	Whose must introduce possession; do not add a spare subject.
This is the school which I studied.	This is the school where I studied.	Where refers to the place of the action.
The person to that I wrote replied.	The person to whom I wrote replied.	Use whom after a fronted preposition in formal style.
The file that I sent it was missing.	The file (that) I sent was missing.	Do not repeat the object with it.

Practice quiz

Choose the sentence that keeps the intended meaning and punctuation. Read the explanation after every answer; the important skill is deciding whether the clause identifies or adds information.

Relative clauses: form, meaning and punctuation

Question 1 of 10

Choose the sentence that identifies which student we mean.

A.The student, who sits near the window, won the prize.B.The student who sits near the window won the prize.C.The student, that sits near the window, won the prize.D.The student which sits near the window won the prize.

Printable relative clauses worksheet

This worksheet works without JavaScript. Rewrite the sentences first, then open the key. Use Print lesson near the top of the page for a classroom copy.

Part A: join the ideas

1. I spoke to a teacher. The teacher runs the debate club. (Use who.)
2. We stayed in a hotel. The hotel overlooked the harbour. (Use that.)
3. My cousin lives in Ghent. She is an architect. (Use a non-defining clause.)
4. I returned the laptop. You lent me the laptop. (Omit the object pronoun if possible.)
5. This is the street. We filmed the interview here. (Use where.)

Part B: add commas or repair the word

6. The app which I use every day is free.
7. Our head teacher that studied in Canada speaks French.
8. The researcher who book won the prize gave a talk.
9. The office where we met last week has moved.
10. The presentation was delayed, that annoyed everyone.

Show worksheet answers and teaching notes

1. I spoke to a teacher who runs the debate club.
2. We stayed in a hotel that overlooked the harbour.
3. My cousin, who is an architect, lives in Ghent.
4. I returned the laptop (that) you lent me. The pronoun is an object and can be omitted.
5. This is the street where we filmed the interview.
6. The app which I use every day is free. No commas if the clause identifies the app.
7. Our head teacher, who studied in Canada, speaks French. Extra information needs commas and who.
8. The researcher whose book won the prize gave a talk.
9. The sentence is correct if the clause identifies the office; no commas are needed.
10. The presentation was delayed, which annoyed everyone. Which refers to the whole previous idea.

A 20-minute classroom activity: the information desk

Goal: learners choose punctuation and relative words based on meaning, not on a memorised list.

1. Prepare, 3 minutes. Write six noun cards: a person, a place, a thing and three familiar names. Add two information cards for each noun.
2. Identify, 6 minutes. Pairs combine cards into defining sentences. The listener must be able to identify the correct person or thing.
3. Add a comment, 5 minutes. Learners turn three defining clauses into non-defining clauses by making the noun specific first, then adding commas.
4. Repair, 4 minutes. Pairs swap sentences and circle every comma, relative word and possible omitted object.
5. Exit check, 2 minutes. Each learner writes one sentence where punctuation changes the meaning and explains the difference aloud.

For assessment, score four features separately: the noun reference, relative word, comma choice and clause word order. A learner can then see whether the problem is meaning, form or punctuation.

Key decisions to remember

• Defining clauses identify the noun and do not use commas.
• Non-defining clauses add information and use commas; do not use that there.
• Use who for people, which/that for things in defining clauses, whose for possession, where for places and when for times.
• Omit a relative pronoun only when it is the object of the clause, not the subject.
• Use punctuation to show the meaning you intend.

Review reported speech for another way to combine ideas, practise time choices in present perfect vs past simple, or search verb patterns in the Verb Pattern Lab.

Grammar references

The examples, questions and classroom materials on this page were written for EnglishDart. Grammar facts were checked against British Council: defining relative clauses, British Council: non-defining relative clauses and Cambridge Grammar: relative pronouns.