Grammar · Lesson 10

Non-defining relative clauses: identify first, then add a side view

A non-defining relative clause adds a separate comment about a person, thing, place, time, group, or whole event that the listener can already identify. The punctuation is part of the meaning. It tells the reader that the inserted information does not select the referent, even though that information may still be important, sensitive, or open to dispute.

70–80 min coreidentity · scope · punctuationwho · which · whose · whom15–20 min extension

NoticeCompare a selected subgroup with an identified whole.

BuildKeep the relative role and punctuation complete.

ConnectUse formal, quantity, and whole-clause patterns.

EditPrevent ambiguity and unsupported background claims.

Can-do: By the end, you can decide from discourse whether a relative clause identifies a referent or adds a separate assertion; punctuate and voice a parenthetical clause; use who, whom, which, whose, where, and when without that or zero relatives; choose conversational preposition stranding or formal preposition-fronting; build quantity patterns such as three of whom and four of which; comment on a whole proposition with which; repair unclear attachment; avoid hiding disputed claims inside background information; and deliver a layered project briefing whose references remain recoverable.

Two-minute retrieval

Reactivate the B1 relative-clause foundation

1The relative word is the subject and cannot disappear: The trainer is available.

2The understood object relative may be omitted because the coordinator is the subject of reserved: The room is available.

3Identify the organization through its associated volunteers: the organization .

4Insert an appositive title with punctuation on both sides: .

Notice how punctuation changes the group

Two consultant records, two different meanings

Record A: Six consultants were considered. Two speak Spanish. The consultants who speak Spanish will lead the bilingual sessions.

Meaning: Only the Spanish-speaking subgroup will lead those sessions. The clause identifies which consultants.

Record B: Three consultants were selected. All three speak Spanish. The selected consultants, who all speak Spanish, will lead the bilingual sessions.

Meaning: The selected group is already identified. The inserted clause adds a separate assertion about all three.

Jordan Lee, who presented the plan on May 14, is the project architect.

The board moved the opening to September 9, which gave the finishing team one more week.

Which clause selects two people from a group of six?
Which clause describes every member of an already selected group?
Which name is already sufficient to identify one person in its context?
What complete decision does the final which comment on?

Discovery check: recover information status

1In Record A, the people who will lead the bilingual sessions are .

2In Record B, the parenthetical clause applies to .

3The noun phrase already identifying the architect before the relative clause is .

4In the opening-date sentence, which refers to .

5A non-defining clause makes .

6A defining clause supplies .

Get to the root: identification comes from discourse

A defining relative clause, also called a restrictive clause, helps identify the intended referent. A non-defining relative clause, also called a nonrestrictive clause, comments on a referent that is already recoverable. Extra means extra for identification. It does not mean unimportant, optional for the writer, or automatically true.

No noun type guarantees one choice. My brother who lives in Seoul can be defining if the speaker has more than one brother and must identify which one. My brother, who lives in Seoul, is non-defining when the listener already knows which brother is meant. A proper name is usually identified in context, but namesakes can require a defining phrase: the Jordan Lee who works for Northline.

Test the discourse, not just the punctuation. Ask: Can the listener recover the referent before the clause? Does the clause select a subset? If I remove the clause, does the intended person or thing remain clear? What separate claim disappears? Then punctuate the meaning you intend.

Meaning first: which context does the punctuation express?

1. The speaker has three brothers, and only one lives in Seoul. Which sentence reports that identifying meaning?

2. The conversation has already focused on one particular brother. Which sentence adds his location without identifying him?

3. The contact list contains two people named Jordan Lee. Which sentence identifies the Northline employee?

4. The approved set is known, and every proposal in it includes a cost estimate. Which sentence expresses that meaning?

5. The archive has 20 reports, and only six contain cost estimates. Which sentence selects the six?

6. The project has one agreed final schedule. Which sentence adds its approval date parenthetically?

Keep the relative role visible

Inside a non-defining clause, the relative expression still fills a grammatical role. Use who for a person as subject; who or more formal whom for a person as object; which for a thing or proposition; whose + noun for association or possession; where for a place relationship; and when for a time relationship.

Standard non-defining clauses do not use that, and the relative expression cannot be omitted even when it is an object: The report, which I read yesterday, was clear, not The report, I read yesterday, was clear. Do not repeat the represented noun with he, she, it, there, or another object inside the clause.

Whose is not limited to people. It can connect organizations and things to an associated noun: Northline, whose bid includes temporary ramps, starts in August; The policy, whose costs remain uncertain, is under review. Agreement follows the noun after whose: whose assistant works, but whose assistants work.

Choose the relative form from its role

1Jordan Lee, , is the project architect.

2Dana Ruiz, , is the library director.

3The final schedule, , is online.

4Jordan Lee, , presented the plan.

5The eastern reading room, , seats 48.

6May 14, , became the new project reference date.

7The policy, , is under review.

8The architect, , visits every Friday.

Use prepositions and quantity patterns deliberately

Conversation often leaves a preposition at the end: Dana Ruiz, who I spoke with yesterday, will attend. More formal prose can place the preposition before whom or which: Dana Ruiz, with whom I spoke yesterday, will attend; The policy, under which staff may work remotely, expires in June. Do not combine both positions.

To comment on members of an identified set, use a quantity expression plus of whom for people or of which for things: five advisers, all of whom...; ten changes, four of which.... The quantity phrase supplies exact scope. The relative word cannot be replaced with that.

Advanced connections: keep the preposition once and the set clear

1. Which version naturally uses conversational preposition stranding?

2. Which version is the formal fronted equivalent?

3. Which sentence says that every one of the five advisers attended both sessions?

4. Which sentence gives the approved quantity precisely?

5. Which sentence reports that zero alternatives met the requirement?

6. Which formal sentence describes what the policy permits?

7. Which formal sentence keeps the application relationship complete?

Let which comment on a whole proposition

A comma plus which can refer to an entire preceding proposition: The board moved the opening to September 9, which gave the team one more week. The cause of the extra week is the whole decision. Whole-clause which commonly introduces an evaluation, consequence, or reformulation: which was unexpected, which means..., which is why....

Attachment must be clear. In The team discussed the budget in May, which was incomplete, a reader may hesitate between budget, the discussion, and even the nearby time phrase. Rewrite the intended relationship: The team discussed the incomplete budget in May or The team discussed the budget in May. That discussion was incomplete.

A parenthetical clause can also make a claim feel settled or backgrounded. Jordan Lee, whose late review caused the delay, apologized asserts a cause as background information. If the source only alleges that cause, attribute it in a main clause: A newsletter alleged that the late review caused the delay, but the project file does not establish that cause. Punctuation does not turn an allegation into fact.

Whole-clause connection: make the intended source recoverable

1. Which sentence clearly presents a reaction to the whole approval event rather than to the plural changes as objects?

2. Which sentence makes the consequence of the scheduling decision clear?

3. Which sentence draws a practical inference from the closure?

4. Which sentence clearly presents the rare materials as the reason for the later reopening?

5. The budget lacked two cost estimates, but the discussion itself was complete. Which revision removes the attachment ambiguity?

6. The budget document was complete, but the discussion omitted staffing. Which revision makes that scope explicit?

7. The only causal claim comes from a neighborhood newsletter. Which sentence reports it without backgrounding it as fact?

Punctuate the meaning, not the length

When a non-defining clause interrupts a sentence, mark both boundaries: The library, which opened in 1986, is being renovated. When the clause comes at the end, one opening comma is enough: The renovation begins in August, which is the quietest month. Do not place a comma after the relative word, and do not add commas merely because a defining clause is long.

Removing the inserted clause should leave a structurally complete main sentence, but it also removes a separate assertion. From The library, which opened in 1986, is being renovated, the main frame is The library is being renovated. The opening date disappears; the library’s identity remains.

Punctuation lab: trace the main frame

1Mark both sides of a parenthetical clause inside the main sentence: .

2The whole-clause consequence comes at the end, so use one boundary before which: .

3The archive has several rooms, and only some contain rare materials. Keep the identifying clause integrated: .

4Do not separate who from the clause it introduces: .

5After removing the opening-date comment, the complete main frame is .

6All members of the already selected adviser group attended, so preserve the parenthetical set meaning: .

Sound natural: signal a side comment without reading commas aloud

Written commas do not require two fixed silent pauses. In U.S. speech, a non-defining clause often forms its own thought group, with a small boundary, a pitch reset, or a lighter parenthetical contour before the speaker returns to the main sentence: Jordan Lee | who presented the PLAN | answered QUESTIONS. The exact pause length varies with speed, emphasis, and clause length.

A defining clause is more tightly integrated with the noun: The consultants who speak SPANISH will lead the bilingual SESSIONS. A non-defining reading can separate the already selected group: The selected consultants | who ALL speak Spanish | will lead the SESSIONS. In formal preposition-fronting, keep the phrase together: with WHOM I spoke. In conversation, who I SPOKE with is natural.

Listen before checking

Ask your tutor to read the five lines naturally. Choose the intended structure, then check your answer.

1Tutor line 1: Clip 1 The integrated clause selects .

2Tutor line 2: Clip 2 The parenthetical thought group describes .

3Tutor line 3: Clip 3 Which refers to .

4Tutor line 4: Clip 4 Recover the formal fronted phrase: .

5Tutor line 5: Clip 5 Recover the conversational phrase: .

Read a project file with reference and evidence intact

Fictional Alder Street Library renovation file

The Alder Street Library, which opened in 1986, is undergoing an accessibility renovation. Project architect Jordan Lee, whose firm won the public bid, presented the revised plan on May 14. Library director Dana Ruiz, with whom Jordan reviewed the plan on May 10, chaired the public meeting.

The plan lists ten changes, four of which the board approved on May 14. Five community advisers, all of whom attended both evening sessions, supported those four changes. The eastern reading room, which seats 48, will reopen on September 9. The archive rooms that contain rare materials will remain closed through October; other archive rooms will reopen in September.

Northline Construction, whose bid includes temporary ramps, will begin work on August 5. The board moved the public reopening from September 2 to September 9, which gives the finishing team one more week. The west entrance will remain closed during construction, which means visitors must use the east entrance.

A neighborhood newsletter alleged that a late design review caused the schedule change. The official project file says the review took longer than forecast, but it does not establish that review as the only cause. A responsible summary attributes the allegation instead of embedding it as an undisputed parenthetical fact about Jordan.

Evidence check: noun comment, set, consequence, or identifying clue?

1. What does the first non-defining clause contribute?

2. What association does the clause about Jordan express?

3. Which sentence preserves the formal review relationship?

4. How many listed changes received approval on May 14?

5. What does all of whom establish about the advisers?

6. Which rooms remain closed through October?

7. What whole event does the first schedule which comment on?

Build the information layers

Builder 1: identified person plus association

Build the sentence; the displayed answer adds the paired commas.

Builder 2: quantity plus of which

Build the quantity report.

Builder 3: whole-clause consequence

Build the decision and its result.

Notice and repair the broken information structure

Repair 1: replace that

Tap the unavailable relative word.

Repair 2: restore the object relative

Tap the phrase where the missing relative word belongs.

Repair 3: remove the repeated object

Tap the extra pronoun.

Repair 4: restore the evidence boundary

Tap the parenthetical claim that the official record does not support.

Say the layers before you reveal them

Guided oral reformulation

Read the exact context, produce one complete sentence aloud, and reveal only after you answer.

1 One identified library + opening date 1986 + current renovation.

The Alder Street Library, which opened in 1986, is being renovated.

2 Ten proposed changes + exactly four approved.

The plan lists ten changes, four of which were approved.

3 Dana Ruiz + I spoke with her + formal fronting.

Dana Ruiz, with whom I spoke, chaired the meeting.

4 Some archive rooms contain rare materials + only those stay closed.

The archive rooms that contain rare materials will remain closed.

5 The board moved the opening + this gave the team one more week.

The board moved the opening, which gave the team one more week.

Play and practice

Games and a short reading that recycle this lesson. Use them as a warm-up, a fast finisher, or homework. Each one checks itself.

Read

Opening the Elm Street kitchen

Read once for meaning. Then read again and do the tasks below.

Neighborhood association newsletter195 wordsAbout 2 min

The Elm Street Community Kitchen, which opened in a former bakery, will host its first public dinner on October 5. Chef Rosa Diaz, whose restaurant closed last year, has agreed to lead the evening cooking classes. Rosa, who grew up three blocks away, says the project feels personal.

The kitchen received twelve volunteer applications, eight of whom have already completed food-safety training. Volunteers who have not finished the training can help with setup, cleaning, and greeting guests until they complete it. The next training session is on September 30.

The dining room, where the bakery once displayed its cakes, now seats forty people at six long tables. The old display counter now serves as a buffet table. The opening date moved from September 28 to October 5, which gave the team time to install a second oven.

Tickets for the first dinner are free, but space is limited. The association recommends booking online by October 1 and asks guests to mention any food allergies on the booking form. Donations of fresh vegetables are welcome on Friday afternoons at the side door. Questions about the dinner can go to the association’s front desk on weekday mornings.

Find it

Tap the relative word (who, whom, which, whose, or where) in each of the 6 non-defining relative clauses. Skip the defining clause.

Check your understanding

1. What does the clause about Rosa Diaz’s restaurant tell us?

2. How many volunteers have completed food-safety training?

3. What did moving the opening date make possible?

Match up

Relative word and its role

Tap an item on the left, then its partner on the right.

Relative word

Role in the clause

Sort it

of whom or of which?

Tap a word, then tap the box it belongs in. Press Check when the tray is empty.

Memory

Conversational and formal prepositions

Flip two cards. If they belong together, they stay. Find every pair in as few turns as you can.

Practice information design without exposing private details

You never need to identify a real family member, coworker, employer, client, medical provider, immigration case, legal dispute, accessibility need, address, private organization, or disputed incident. Use Alder Street, public information with reliable sourcing, or tutor-created fictional profiles. The lesson tests information status and reference, not personal disclosure.

Scope switch: Invent six candidates, two of whom have one relevant skill. Give a defining sentence that selects the two. Then establish a selected group whose members all share another feature and add that feature parenthetically.

Register switch: Describe one fictional professional first with who I spoke with and then with with whom I spoke. Keep the relationship constant and explain which channel suits each version.

Quantity report: Introduce a set of people and a set of proposals. Add all of whom, two of whom, three of which, or none of which with exact fictional counts.

Attachment edit: Create an intentionally unclear which sentence. Rewrite it once as a noun comment and once as a whole-proposition comment.

Source check: Turn one unsupported parenthetical claim into an attributed main clause with a clear evidence limit.

Final production and check

Final production: deliver a 90-second layered project briefing

Use Alder Street or another tutor-supplied fictional project. Begin with an already identified project, person, place, and date. Add one subject who clause, one object which clause, one whose + noun clause, and one where or when clause. Contrast one defining subgroup with one non-defining whole-group comment. Use one of whom/of which quantity, one formal fronted preposition or conversational stranded preposition, and one unambiguous whole-clause which. Mark the parenthetical thought groups naturally. When the editor challenges an inserted claim, identify its source, move it into a main clause, or remove it.

Success criteria: Can the listener recover every referent before each side comment, distinguish selected subgroup from identified whole, locate the relative word’s role, hear the parenthetical boundaries, recover the exact quantity and preposition relationship, identify the source of a whole-clause consequence, and separate supported background information from disputed claims?

Final check: defend the information structure

1. A larger adviser group existed, but only session attendees supported the plan. Which sentence preserves that subgroup meaning?

2. Which sentence has a complete non-defining object relative?

3. Which formal sentence controls the preposition pattern?

4. Which sentence reports the exact approved share?

5. Which sentence gives which an unambiguous whole-clause source?

6. Which sentence reports an unresolved cause responsibly?

Reflect: what does the listener know before the clause?

Explain the information-status path

Complete these ideas aloud: The listener can identify the referent because... The clause selects / separately asserts... The relative expression fills the role of... The main frame is... The exact set quantity is... The preposition belongs... Whole-clause which refers to... The source supports... The source does not establish...

Then take one sentence from your briefing. Remove the inserted clause and state what identity remains and what assertion disappears. Add the clause again, say it as a parenthetical thought group, and check whether its source and attachment remain clear.

Return tomorrow for the five-item retrieval check before rereading the lesson.

Next-day retrieval

Return without rereading the page. Recover the intended set, relative role, quantity, whole-clause source, and claim status from new fictional contexts.

Five delayed checks

1. Only applicants with references advanced. Which sentence preserves that scope?

2. Which sentence has the required object relative and no repeated pronoun?

3. Which sentence gives the remote-speaker quantity precisely?

4. Which sentence gives which a clear whole-clause source?

5. Which sentence reports a disputed cause without hiding it in a parenthetical clause?