What Is a Relative Clause? KS3 English Definition, Examples and Usage

A relative clause is a type of subordinate clause that gives extra information about a noun. It is introduced by a relative pronoun — who, which, that, whose, or whom — and cannot stand alone as a sentence. Without it, the sentence still makes sense; with it, the noun is precisely identified or described.

What are the relative pronouns and when do you use each one?

The choice of relative pronoun depends on what the clause is referring to:

Whom is formal and now rare in spoken English, though it is still expected in formal written work. Many writers use "who" for both subject and object positions in everyday writing; "whom" earns a mark for accuracy in formal contexts.

What is the difference between defining and non-defining relative clauses?

This distinction is one of the most important in punctuation — and one of the most frequently tested:

Defining (restrictive) relative clause: The clause is essential to the meaning. Without it, you would not know which specific noun is being referred to. No commas are used.

"The student who wins the prize will represent the school."

Remove the clause and the meaning is vague: "The student will represent the school" — which student? The relative clause defines the noun by narrowing it to a specific one.

Non-defining (non-restrictive) relative clause: The clause adds extra information about a noun that has already been specifically identified. Commas surround it because it could be removed without changing the core meaning.

"Amara, who won the prize, will represent the school."

Amara is already identified by name. The relative clause adds information but is not needed to identify which Amara. Remove it and the sentence is still complete: "Amara will represent the school."

The comma is the signal: commas = non-defining; no commas = defining.

How do writers use relative clauses for literary effect?

In skilled writing, relative clauses are used to layer description efficiently, creating a dense, precise prose style. A single sentence can introduce a character, establish their role, and hint at their motivation:

Worked example:

"The woman who had lived alone for eleven years and whose only companion was a cat that understood nothing stood at the window and watched the street fill with strangers."

Three relative clauses are embedded here. The first establishes isolation, the second deepens it with a note of dark comedy, and "that understood nothing" (a defining clause with no comma) is precise — it identifies which cat while simultaneously commenting on the futility of the companionship. All of this characterisation happens before the main verb ("stood") arrives, building the reader's picture of the character before we see what she does.

What is a reduced relative clause?

A reduced relative clause is one where the relative pronoun (and sometimes the auxiliary verb) has been omitted to create a more concise construction. They are common in formal and literary writing:

Reduced clauses use a past participle (parked, chosen, written) in place of the full pronoun + verb. Recognising them in an exam text shows grammatical awareness.

How are relative clauses tested in exams?

Relative clauses appear in GCSE English Language exams in two ways. First, as something to identify and analyse in a reading text — a question about language might reward you for noticing how a relative clause characterises, slows the pace, or layeres detail. Second, as something to use accurately in your own writing, especially in formal extended tasks. Using a range of clause types — including relative clauses — demonstrates syntactic control and earns marks for technical accuracy.

At KS3, they are regularly tested in grammar and SPaG exercises, where students must add or punctuate relative clauses correctly.

Frequently asked questions

Can I use "that" instead of "who" when referring to a person?

In defining relative clauses, "that" is acceptable when referring to people in informal writing: "the student that won" is widely used. However, in formal writing and exam responses, "who" is considered more appropriate for people. Never use "which" for people — "the student which won" is a grammatical error.

How do I know if a relative clause needs commas?

Ask yourself: if I remove this clause, does the sentence still identify the same specific noun? If yes, use commas (non-defining). If the clause is needed to identify or narrow down which noun you mean, use no commas (defining). Another way: if you can wrap the clause in brackets and the sentence still makes complete sense, it is non-defining and needs commas.

Can I start a sentence with a relative clause?

Not easily, because a relative clause must follow the noun it modifies, and that noun is usually within a sentence rather than at the start. What you can do is place the modified noun at the start, immediately followed by the clause: "Whoever arrives first will choose the room" — but "whoever" here is functioning as a fused relative pronoun (its own antecedent) rather than a typical relative clause.

What is the most common mistake with relative clauses?

Forgetting the comma before a non-defining clause. "My brother who is a doctor lives in Leeds" is technically correct only if you have more than one brother and this clause identifies which one. If you have one brother, you need "My brother, who is a doctor, lives in Leeds." Students also frequently use "which" for people — always use "who" or "whom" for human referents in formal writing.

Work through relative clause exercises with Professor Quill at aitutors.me — he will give you sentences to complete and correct until the distinction between defining and non-defining becomes second nature.