Practise this grammar point with a scored quiz, sentence exercises and writing tasks—all with explanations or review guidance.
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Defining clauses narrow down a group. Non-defining clauses add a comment about a noun already identified. Punctuation changes meaning, so decide what the reader already knows.
| Use | Example | Why it works |
|---|---|---|
| Identifying a subset | Students who finished may leave. | Only the students who finished may leave. |
| Adding information | The students, who had finished, left. | The clause says the already identified students had finished. |
| Pronoun choice | My phone, which is new, works well. | A non-defining clause uses which, not that, for a thing. |
Check: Adding commas without checking meaning
Use: Choose punctuation after deciding what identifies the noun
Commas can turn an identifying condition into extra information.
Read the example and explain the choice before answering. After the exercise, write a new sentence using the same pattern. Revisit any answer you could not explain, even if you guessed correctly.
4 sets · 40 exercises · about 50–70 minutes with writing and review.
10 scored questions, 20 sentence exercises and 10 writing challenges. Time depends on your pace. Start with the quiz or choose the practice you need.
Your scored quiz and self-reviewed exercises are tracked separately on this device.
Questions 1–5 build confidence; 6–10 check transfer and detail. Use Practice for feedback after each answer, or Test yourself to check at the end.
10 questions · 10 XP per correct answer · explanations included
The students who passed celebrated.. Without commas, the clause identifies which students celebrated.
My tutor, who lives nearby, cycles.. The commas mark supplementary information.
My car, which is old, works.. A non-defining clause about a thing uses which.
Omit the object pronoun. The email you sent arrived is grammatical: the object relative pronoun is omitted.
Whether the clause identifies or adds information. The meaning and identifying role determine the punctuation.
Only the brothers living abroad.. The defining clause restricts the group to brothers living abroad.
Extra information about the brothers.. The commas mark a non-defining clause, giving extra information about the identified group.
The phone which I bought is broken.. Which can become that in the defining clause without commas, but not in the two non-defining clauses.
The bag that I lost was red.. That is an object in the first sentence. Non-defining pronouns and full-clause subject pronouns stay.
The boxes that were damaged were replaced.. The defining clause selects damaged boxes rather than presenting all boxes as damaged.
Complete the missing words, then compare the expected form. More than one natural answer may be possible; use the cue and explanation.
who arrived early
Only some guests arrived early: The guests who arrived early got front seats. (add the restricting clause)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
who live abroad
All my cousins live abroad: My cousins, who live abroad, are visiting. (add extra information)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
who owns a shop
This named person owns a shop: Maya, who owns a shop, works long hours. (add extra information)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
that you recommended
Select one book: The book that you recommended was excellent. (use that)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
which I bought last month
Add information about my identified bike: My bike, which I bought last month, is red. (use which)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
that were damaged
Only damaged boxes were replaced: The boxes that were damaged were replaced. (use that)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
which were damaged
Add information about all these boxes: These boxes, which were damaged, were replaced. (use which)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
who manages the café
Identify the person by their job: The woman who manages the café is here. (use who)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
whose sister is a chef
Add a detail about a named person: Omar, whose sister is a chef, enjoys cooking. (use whose)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
where we met
Select the relevant room: The room where we met is upstairs. (use where)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
Complete the missing words, then compare the expected form. More than one natural answer may be possible; use the cue and explanation.
which
In a non-defining clause, use which rather than that for a thing.
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
object
In the book that I read, that is an object and may be omitted. (subject/object)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
subject
In the book that fell, that is a subject and cannot simply be omitted. (subject/object)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
two
Extra information in the middle of a sentence needs two commas. (one/two)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
defining
A clause that identifies a subset is defining. (defining/non-defining)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
non-defining
A clause adding information about a named person is usually non-defining. (defining/non-defining)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
only the students who passed
The students who passed refers to only the students who passed. (give the restricted group)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
extra information
The students, who passed, presents passing as extra information about the identified students.
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
cannot
A relative pronoun in a non-defining clause cannot normally be omitted. (can/cannot)
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
that
In a defining clause about a thing, which can often be replaced by that.
Decide whether the clause selects a subset or adds information about an already identified noun. Commas affect meaning.
Write an original answer for each task. Review the guidance to check your work. These are self-review tasks, not automatic grammar grading.
Your wording can vary.
Use a defining who clause without commas.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Use a non-defining who clause and commas.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Explain the restricted group versus the whole identified group.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Use which or that to identify the item.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Use which and commas; do not use that.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Keep the clause’s subject and verb intact.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Non-defining relative pronouns are retained.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Use whose in a defining clause without commas.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Use whose in a clause set off by commas.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Your wording can vary.
Choose whether you mean a subset or the entire group and punctuate accordingly.
Check both the form and the meaning. If you are unsure, compare the lesson explanation before marking this exercise reviewed.
Print this lesson’s original questions with a separate answer key. Use the worksheet for another round without looking at the explanations.
Try these two tasks before opening the answers. They practise explanation and writing; they do not change your quiz score.
Explain: The tickets that were discounted sold quickly. / The tickets, which were discounted, sold quickly.
The first identifies the discounted tickets as the ones that sold quickly. The second adds that the already identified tickets were discounted. Punctuation changes the information structure.
Only students who registered may enter. Write a sentence making that restriction clear.
Students who registered may enter. Do not surround the identifying clause with commas; it restricts permission to that group.
Other wording may be correct. Compare the meaning and verb pattern, not just the words.
Identify exactly which person or thing you mean.
Choose the time you have. These are suggested study plans, not timers.
Answer the ten-question quiz. Read the explanation for each mistake before trying again.
Take the scored quiz →30 MINComplete the warm-up, then sets 2 and 3. Compare your answers and correct the patterns you missed.
Open sentence practice →60 MINWork through all four sets. Spend the final part writing, comparing and improving your own sentences.
Explore all four sets →Open the question that matches where you got stuck.
A defining clause identifies which person or thing: “The students who revised passed.” A non-defining clause adds information about an already identified group: “The students, who revised, passed.” The first selects a subset; the second comments on the group.
Deletion is a useful test, but ask whether the intended identity stays clear. Both versions may remain grammatical. The real question is whether the clause selects who or what you mean, not whether the sentence can survive without it.
A fresh set of 10 questions with explanations. Continue when you are ready.
Next challenge: Reduced relative clauses →