To learn English relative clauses quickly and correctly, begin with the information your reader needs about a person or thing. A relative clause lets you combine ideas without repeating the same noun: “The girl who won the race is my friend.” The extra words identify which girl we mean. Other relative clauses add helpful, non-essential details. This English Quick Notes lesson teaches a small decision method for who, which, that, whose, where and when, along with commas, common mistakes and a practice quiz.
- Find the noun: identify the person, thing, place or time you want to describe.
- Choose the relationship: who for people, which for things, whose for possession, and sometimes where or when.
- Decide whether the information is essential: defining clauses identify; non-defining clauses add extra detail.
- Check commas: defining clauses normally have no surrounding commas; non-defining clauses usually do.
- Check the verb: match it to the noun the relative pronoun represents.
- Check omission: in some defining clauses, an object relative pronoun may be left out.
Teaching step 1 — combine two sentences around one noun. Start with “The boy lives next door. The boy plays chess.” Both sentences mention the same boy. Combine them: “The boy who lives next door plays chess.” The clause who lives next door identifies which boy. You do not need to repeat the boy. Read the sentence without the clause; if the reader would not know which boy you mean, the clause is probably essential to identifying him.
Teaching step 2 — choose the correct linking word. “The student who helped me was kind.” A person is being described. “The book that I borrowed was useful.” A thing is being described. “The student whose notebook was lost found it.” This shows possession. Do not choose a word only because it sounds formal. Identify whether the clause refers to a person, a thing, an owner, a place or a time.
Teaching step 3 — decide whether the clause needs commas. Compare “The pupils who finished early could read quietly” with “Mrs Tan, who teaches our class, enjoys gardening.” In the first, the clause selects which pupils we mean, so it is defining and normally has no commas. In the second, the named person is already identified; the clause adds extra information and is set off by commas. Punctuation changes how the reader interprets the sentence.
What is a relative clause?
A relative clause is a dependent clause connected to a noun or noun phrase. It can identify the noun or give additional information about it. “The bicycle which I bought yesterday is red.” The relative clause which I bought yesterday adds information about the bicycle. It helps readers understand which bicycle you are talking about.
The useful relative words at a glance
- Who: commonly refers to people — “The pupil who answered was confident.”
- Which: commonly refers to things or animals — “The diagram which shows the circuit is useful.”
- That: can refer to people or things in many defining clauses — “The song that we heard was beautiful.”
- Whose: shows possession or an association — “The girl whose bag went missing found it.”
- Where: can introduce a place-related clause — “This is the park where we met.”
- When: can introduce a time-related clause — “I remember the day when we first spoke.”
- Whom: is a formal object form for people — “The person whom I invited arrived.” Everyday English often uses who instead.
Not all of these words have the same grammatical function. Who, which, that and whose can function as relative pronouns in the relevant patterns; where and when function as relative adverbs. For most beginner writing, the important skill is choosing a form that makes the relationship clear and natural.
Defining relative clauses: information you need
In “The learner who solved the puzzle received a prize,” the clause identifies which learner received it. Without that clause, the identity might be unclear. Defining relative clauses are also called restrictive relative clauses. They normally do not have commas around them.
- People: “The neighbour who helped us is a doctor.”
- Things: “The pencil that I borrowed is on the desk.”
- Place: “The café where we met is closed today.”
- Time: “The year when we moved was challenging.”
- Possession: “The child whose shoes were missing looked worried.”
The crucial question is “Does this clause tell the reader which one?” If yes, treat it as essential identifying information. It need not be dramatic. Even a simple phrase such as that we bought yesterday can do important work when several objects could match the noun.
Non-defining relative clauses: extra detail
In “My sister, who lives in Penang, is visiting,” the noun phrase my sister may already identify the person in that context. The clause adds information. It is usually separated by commas. You can often remove it and still identify the main subject: “My sister is visiting.” This is called a non-defining or non-restrictive relative clause.
- Person: “Ms Lim, who teaches music, organised the concert.”
- Thing: “The science museum, which opened a new exhibition, welcomed visitors.”
- Place: “Singapore, where our school is located, has a tropical climate.”
- Possession: “Arun, whose brother plays football, joined our team.”
A key rule for formal school writing: do not use that to introduce a non-defining relative clause. Write “My bicycle, which I repaired yesterday, works well,” not “My bicycle, that I repaired yesterday, works well.” The commas and the relative word need to match the type of clause.
The comma test: compare two sentences
- Defining: “The students who completed the homework may leave.” This refers only to students who completed it.
- Non-defining: “The students, who completed the homework, may leave.” This presents completion as extra information about an already identified group.
- Meaning: punctuation can change which people are included. Do not add commas simply because you pause while reading.
Use the comma test in compositions and explanations, particularly when you describe groups. “Children who enjoy reading” selects a subset of children. “My children, who enjoy reading,” adds a comment about children who are already identified. One pair of commas can change the logic of your sentence.
Subject and object relative pronouns
Relative word as subject
“The teacher who explains clearly is popular.” In the relative clause, who is the subject of explains. You cannot simply omit it: “The teacher explains clearly is popular” is not the intended standard relative-clause structure. The verb also agrees with the person or thing referred to. “The students who explain clearly” uses the plural form.
Relative word as object
“The story that I read was interesting.” In the clause, I is the subject and that represents the object of read. You can omit this object relative pronoun in a defining clause: “The story I read was interesting.” This is natural English. Do not apply the omission rule to the subject relative pronoun, and do not normally omit the relative pronoun from a non-defining clause.
The quick omission check
- Can omit: “The film that we watched was exciting.” → “The film we watched was exciting.”
- Can omit: “The friend who I called answered.” → “The friend I called answered.”
- Cannot ordinarily omit: “The boy who won the race smiled.” The relative pronoun is the subject of won.
- Do not normally omit in a non-defining clause: “My aunt, who lives nearby, is visiting.”
This is a useful way to make writing shorter without losing meaning. But omission is not compulsory. If leaving in who, which or that makes the sentence clearer, keep it. The priority is an easy-to-follow sentence.
Whose: show ownership accurately
Use whose when the relative clause expresses possession or a related association: “The athlete whose shoes were missing arrived late.” The shoes belong to the athlete. Unlike who’s, which can mean who is or who has, whose has no apostrophe. The word can also refer to things in formal constructions, such as “a company whose products are popular.”
Where and when: link a place or time
“The room where we study is quiet” tells us about a place. “The day when school reopened was exciting” tells us about a time. You may also find “the room in which we study” or “the day on which school reopened.” These are more formal alternatives. When using where, do not add a redundant place expression: “the place where we met,” not “the place where we met there” in the same ordinary construction.
Prepositions in relative clauses
Compare “The person who I spoke to was helpful” with “The person to whom I spoke was helpful.” Both are grammatical; the second is more formal. With a thing, compare “The chair that I sat on” with “The chair on which I sat.” You do not need a complicated form in a basic composition. Choose a clear natural sentence and ensure the preposition belongs to the verb or expression.
Five frequent mistakes and corrections
- Incorrect: “The girl which won the prize is here.” Correct: “The girl who won the prize is here.”
- Incorrect: “The book who I read was helpful.” Correct: “The book that I read was helpful.”
- Incorrect: “Our tutor, that explained the answer, was patient.” Correct: “Our tutor, who explained the answer, was patient.”
- Incorrect: “The boy who he called me is waiting.” Correct for the intended subject: “The boy who called me is waiting.”
- Incorrect: “This is the shop where I bought it there.” Correct: “This is the shop where I bought it.”
A three-question relative-clause check
- 1. Which noun am I describing? Underline it and decide whether it names a person, thing, place, time or owner.
- 2. Is the extra information essential? Use no surrounding commas for defining clauses; normally add commas for non-defining clauses.
- 3. Is the sentence grammatical? Check the relative word, the clause’s subject and verb, any pronoun omission and unnecessary repeated words.
Quick practice: choose the best word or punctuation
- 1. The student ___ helped me is in my class. (who / which)
- 2. The worksheet ___ I finished is on the table. (that / whose)
- 3. The child ___ mother is a nurse brought a first-aid kit. (whose / who’s)
- 4. This is the place ___ we played football. (where / when)
- 5. I remember the day ___ we first met. (when / where)
- 6. My uncle, ___ lives overseas, is visiting soon. (who / that)
- 7. The books ___ are on the shelf belong to Ravi. (that / whose)
- 8. The story ___ we read yesterday was exciting. (which / who)
- 9. Which is the natural defining clause? (A) “The boy who I spoke to was helpful.” (B) “The boy, that I spoke to, was helpful.”
- 10. Can that be omitted here? “The film that we watched was funny.” (yes / no)
Answers and explanations
- 1. who — the clause describes a person who is its subject.
- 2. that — refers to the worksheet, the thing finished.
- 3. whose — shows that the mother belongs to the child’s family; no apostrophe.
- 4. where — refers to a place.
- 5. when — refers to a time.
- 6. who — non-defining clause for a person; that does not fit.
- 7. that — the relative clause identifies which books.
- 8. which — refers to a thing; that could also work in this defining clause.
- 9. A — the identifying clause is not set off by commas.
- 10. yes — that is the object within the defining clause, so “The film we watched was funny” works.
A five-minute relative-clause routine
- Minute 1: join two sentences about one person using who.
- Minute 2: join two sentences about an object using which or that.
- Minute 3: write one sentence with possession using whose.
- Minute 4: compare one defining clause and one non-defining clause; check commas.
- Minute 5: practise omitting an object relative pronoun without losing meaning.
Frequently asked questions
Are who and that always interchangeable?
No. In many defining clauses about people, both can be used. But non-defining relative clauses do not normally use that: “Mrs Lee, who teaches us, is kind.” When in doubt, who is a useful choice for a person.
Why are commas so important?
They tell readers whether the clause is identifying a person or thing, or merely adding further detail. The difference can change who is included in the statement. Treat punctuation as part of meaning, not decoration.
Can I leave out the relative word?
Sometimes. In a defining clause where it functions as the object, “the book I bought” is natural. But “the student won the prize is here” is not the ordinary form when the missing word is the subject. Use “the student who won the prize.”