Language

Relative Clauses

The Spark

Concept

A relative clause adds information about a noun using a relative pronoun — who (for people), which (for things), that (for people or things). A defining relative clause identifies which person or thing we mean. A non-defining relative clause adds extra information and is separated by commas.

Activity

Point to an object in the room and ask your child to describe it using who, which or that — for example, That is the chair which we bought last year. Practise with a few examples before starting the worksheet.

Check

After the worksheet, ask your child to write three sentences — one with who, one with which, one with that — about people or objects in their home.

1

Choose Who, Which or That (Set A)

Circle the correct relative pronoun to complete each sentence.

The scientist ___ discovered penicillin was Alexander Fleming.

who
which
what

The book ___ I borrowed from the library was fascinating.

who
which
what

The children ___ finished early were allowed to read.

which
who
what

The bridge ___ was built in 1932 is still standing.

who
which
what

Is this the dog ___ won the competition?

who
that
what
3

Match the Relative Pronoun to Its Use

Draw a line to match each relative pronoun with its correct use.

who
which
that
whose
where
when
Used for time (the year __ they met)
Used for people
Used for things, especially non-defining
Used for possession (the girl __ cat is missing)
Used for things or people in defining clauses
Used for places
TipKeep this rule simple: who = people, which = things, that = people or things (in defining clauses), whose = possession.
4

Sort: Defining or Non-defining? (Set A)

Sort each sentence into the correct column. Defining relative clauses tell us which specific person or thing — no commas needed. Non-defining relative clauses add extra information — commas required.

The car that is parked outside belongs to our neighbour.
My grandmother, who lives in Perth, is visiting next month.
The student who scored highest received a certificate.
The Great Barrier Reef, which stretches 2,300 km, is under threat.
Athletes who train daily improve faster than those who do not.
Our dog, which we rescued two years ago, loves the beach.
Defining (no commas)
Non-defining (uses commas)
TipA useful test: if you can remove the clause and still know which person or thing is meant, it is likely non-defining. If removing it makes the sentence unclear, it is defining.
6

Combine the Sentences (Set A)

Combine each pair of sentences into one using a relative clause with who, which or that.

1. The woman won the race. She had been training for a year. Answer:

2. The laptop belongs to my dad. It has a cracked screen. Answer:

3. The building was demolished last year. It used to be a cinema. Answer:

4. My neighbour keeps chickens. She gives us eggs every week. Answer:

7

Does This Sentence Need Commas?

Circle Yes (needs commas — non-defining) or No (no commas — defining) for each sentence.

The dog that bit the postman was taken to a vet.

Yes — add commas
No — no commas needed

My sister who lives in Adelaide is a doctor.

Yes — add commas (if only one sister)
No — no commas needed

The house that we lived in has been sold.

Yes — add commas
No — no commas needed

Sydney which is Australia's largest city is on the east coast.

Yes — add commas
No — no commas needed

Students who complete the extension task will earn a bonus point.

Yes — add commas
No — no commas needed
8

Expand and Improve (Set A)

Rewrite each simple sentence by adding a relative clause to make it more precise and interesting. Choose the correct relative pronoun and decide whether commas are needed.

1. The explorer made an important discovery. Expanded:

2. The library has a new reading room. Expanded:

3. My teacher gave us extra homework. Expanded:

4. The documentary was very interesting. Expanded:

TipRemind your child that a relative clause should add meaningful information. Ask: Does this clause help the reader understand more clearly?
9

Match: Which Relative Pronoun Is Used?

Read each sentence. Draw a line to the relative pronoun used in it.

The house where I grew up has been painted.
The year when she was born was very cold.
The friend whose book I borrowed has moved away.
The cat that climbed the tree refused to come down.
My uncle, who is a chef, visited us last week.
that
who
whose
where
when
11

Relative Pronoun or Something Else?

In each sentence, decide whether the underlined word is used as a relative pronoun or in a different way.

The book THAT she read was excellent.

Relative pronoun
Conjunction
Demonstrative pronoun

WHAT he said surprised everyone.

Relative pronoun
Interrogative pronoun
Demonstrative pronoun

The scientist WHO won the prize was very humble.

Relative pronoun
Interrogative pronoun
Conjunction

WHICH way did they go?

Relative pronoun
Interrogative adjective
Conjunction

The letter WHICH arrived this morning was from overseas.

Relative pronoun
Interrogative pronoun
Conjunction
12

Write Your Own Relative Clauses (Set A)

Write six sentences about people or places you know. Each sentence must contain a relative clause using who, which or that. Label each clause — D for defining or ND for non-defining.

1.

2.

3.

4.

5.

6.

14

Build a Sentence with a Relative Clause

Rearrange each set of words and phrases into a grammatically correct sentence containing a relative clause.

?
the dog / that / barked all night / belongs to / our new neighbours
?
the painting / which / hangs in the hall / was / a gift from my grandmother
?
the student / who / studied hardest / won / the science prize
?
Mount Kosciuszko / which / is the highest peak in Australia / is in / New South Wales
17

Sort: Who, Which, That, Whose or Where?

Sort each sentence into the column that shows which relative pronoun would complete it.

The teacher ___ taught me Year 4 was very patient.
The letter ___ arrived this morning was from the school.
The park ___ we walk our dog is nearby.
The child ___ painting won first prize was delighted.
That is the film ___ won three awards.
The city ___ she was born has changed a lot.
The player ___ scored the winning goal celebrated with her team.
Australia, ___ has a unique biodiversity, is home to many native species.
who
which
that / who
whose
where
18

Relative Clauses in Descriptive Writing

Write a descriptive paragraph (6 to 8 sentences) about a place you know well — your home, your local park, your favourite room. Include at least three relative clauses. Label each one in the margin.

My place:

My paragraph:

Draw here
23

Combine Four Sentences Using Relative Clauses

Combine these four short sentences into one or two longer, fluent sentences using relative clauses. You may use any relative pronoun.

The ancient library was built in 1890. It stood on the corner of King Street. Many famous writers studied there. It was demolished last year. Combined:

Draw here

Our science teacher is Mrs Hadley. She studied at Melbourne University. She wrote a book about native birds. The book was awarded a prize. Combined:

Draw here
24

Sort: Relative Clause Position

A relative clause can appear in different positions in a sentence. Sort each sentence by where the relative clause appears.

The girl who won the race trained every day.
I gave the trophy to the student who worked hardest.
She lived in the house that stood at the end of the lane.
The dog that barked all night finally fell asleep.
He handed the envelope to the person whose name was written on it.
We visited the museum where the exhibition was held.
Clause after the subject noun
Clause after the object noun
Clause after a preposition phrase
25

Relative Clauses and Sentence Variety

Rewrite this passage to add at least four relative clauses. The passage should become more detailed and precise. Label each relative clause you add.

ORIGINAL PASSAGE: The bakery is on Main Street. It is run by a woman. She bakes bread early every morning. The bread sells out by nine o'clock. The bakery has a cat. It sleeps in the window. Rewritten passage with relative clauses:

Draw here
TipAdding relative clauses is one of the most effective ways to increase sentence complexity without losing clarity. Read the finished passage aloud to check it flows well.
27

Choose Who, Which or That (Set B)

Circle the correct relative pronoun.

Australia is a country ___ has a unique range of wildlife.

who
which
what

The surgeon ___ operated on her was highly experienced.

which
who
what

They stayed in a hotel ___ had a rooftop pool.

who
which
what

She is the type of person ___ always makes time for others.

which
who
what

Is this the road ___ leads to the lighthouse?

who
that
what

The reason ___ she was late is still unclear.

why
which
who
29

Relative Clauses in Information Writing

Write a short informational paragraph (6 to 8 sentences) about an animal, a historical figure or a natural landmark. Include at least three relative clauses. Your relative clauses must add genuinely useful information.

My topic:

My paragraph:

Draw here
TipInformation writing with relative clauses reads more fluidly than lists of short sentences. Compare a version with relative clauses to the original short-sentence version to show the difference.
32

Sort: Correct or Incorrect Use of Relative Pronoun?

Sort each sentence into the correct column.

The scientist which discovered penicillin was Fleming.
The scientist who discovered penicillin was Fleming.
The city where she was born has changed a lot.
The city which she was born has changed a lot.
The student whose work won the prize was delighted.
The student which work won the prize was delighted.
Correct
Incorrect — wrong relative pronoun
33

Correct the Relative Clause Errors

Each sentence below has an error in its relative clause. Identify the error and rewrite the correct sentence.

1. The house which my grandparents live is on a hill. Error: _______________ Corrected:

2. The student which won the prize was very surprised. Error: _______________ Corrected:

3. She is a person who's ideas are always interesting. Error: _______________ Corrected:

4. The film, that we saw last week, was brilliant. Error: _______________ Corrected:

TipIdentifying and explaining errors is harder than writing correctly from scratch — it requires metalinguistic awareness. Praise careful reasoning.
35

Relative Clauses in a Persuasive Argument

Write a persuasive paragraph (6 to 8 sentences) arguing for or against a cause you care about. Include at least three relative clauses to add precision and detail to your argument.

My argument (for or against what?):

My persuasive paragraph:

Draw here

Relative clauses I used (underline in your paragraph and list here):

TipRelative clauses in persuasive writing allow writers to pack precise, relevant detail into their arguments without writing very long sentences. They signal a sophisticated writer.
38

Spot and Collect: Relative Clauses in Published Texts

Find five relative clauses in newspapers, non-fiction books or novels. Copy each sentence, underline the relative clause, and identify whether it is defining or non-defining.

1. Source and sentence (with clause underlined), defining or non-defining:

2.

3.

4.

5.

39

Punctuate the Relative Clause Correctly

Read each sentence. Circle the correctly punctuated version.

Choose the correctly punctuated version:

The Eiffel Tower which is in Paris attracts millions of tourists.
The Eiffel Tower, which is in Paris, attracts millions of tourists.

Choose the correctly punctuated version:

Students, who study regularly, tend to perform better.
Students who study regularly tend to perform better.

Choose the correctly punctuated version:

The car that I drive needs a service.
The car, that I drive, needs a service.

Choose the correctly punctuated version:

My grandfather, who was born in 1942, still loves cricket.
My grandfather who was born in 1942 still loves cricket.
43

Transform: Relative Clause to Participial Phrase

Rewrite each sentence by replacing the relative clause with a participial phrase. Discuss with your parent whether the new version sounds better, worse or just different.

1. The dog that was barking at the gate finally quietened down. Participial phrase version:

2. The student who had passed the exam was congratulated. Participial phrase version:

3. The house that was built in the 1920s is now a heritage site. Participial phrase version:

4. The team that was training for the championships worked incredibly hard. Participial phrase version:

TipThere is no single right answer here — the goal is awareness of stylistic choice. Both versions may be equally correct; the question is which is more appropriate for the context.
44

Sort: Relative Clause or Participial Phrase?

Sort each sentence modifier into the correct column.

...who discovered the vaccine...
...covered in mud...
...which was awarded a prize...
...running towards the finish line...
...whose research changed medicine...
...exhausted after the long journey...
Relative clause (who/which/that/whose/where)
Participial phrase (-ing or -ed)
46

Misplaced Relative Clause: Find the Error

Each sentence has a misplaced relative clause. Circle the version that corrects it.

ERROR: I found a coin in the park that was very old.

I found a very old coin in the park.
I found a coin that was very old in the park.
In the park, I found a coin that was very old.

ERROR: She bought a vase from the antique shop which was cracked.

From the antique shop, she bought a vase which was cracked.
She bought a cracked vase from the antique shop.
She bought a vase which was cracked from the antique shop.

ERROR: He gave the medal to his father, who had worked so hard, at the ceremony.

He gave the medal, which his father had worked so hard for, to him at the ceremony.
At the ceremony, he gave the medal to his father, who had worked so hard.
He gave his father, who had worked so hard, the medal at the ceremony.
47

Fix the Misplaced Relative Clauses

Rewrite each sentence to fix the misplaced relative clause so the meaning is clear.

1. She gave a cake to her teacher that was covered in chocolate. Fixed:

2. I saw a dog in the street which had only three legs. Fixed:

3. He lent his umbrella to a stranger that he never saw again. Fixed:

4. We watched a film about a scientist which lasted three hours. Fixed:

50

Write a Character Description Using Relative Clauses

Write a character description of a person you invent or know. The description should be 8 to 10 sentences long and include at least four relative clauses — at least two defining and at least two non-defining. Label each one in the margin.

My character:

Draw here
TipCharacter descriptions are an excellent context for relative clauses: 'She was the kind of person who never forgot a birthday...' 'Her house, which she had inherited from her grandmother, was full of books...'
51

Sort: Relative Clause or Subordinate Clause?

Sort each underlined clause into the correct column.

The student who studied every day passed the test.
She passed the test because she studied every day.
The book which she read changed her life.
Although it was raining, they went for a walk.
The park where they used to play has been redeveloped.
If she studies hard, she will succeed.
Relative clause (introduced by relative pronoun)
Subordinate clause (introduced by conjunction: because, although, if, when, etc.)
54

Relative Clauses and Sentence Rhythm

Read these two versions of the same paragraph. Then answer the analysis questions.

VERSION A (no relative clauses): The museum was built in 1895. It stands on Flinders Street. It houses over 10,000 artefacts. These artefacts document the history of Victoria. The curator is a woman. She has worked there for thirty years. VERSION B (with relative clauses): The museum, which was built in 1895, stands on Flinders Street and houses over 10,000 artefacts that document the history of Victoria. The curator, who has worked there for thirty years, oversees the entire collection. 1. Which version is easier to read and why?

2. How many relative clauses are in Version B? List them.

3. Are the relative clauses in Version B defining or non-defining? Explain.

55

Choose the Best Relative Clause for the Context

Read each sentence. Circle the relative clause that best completes it in terms of precision, relevance and style.

The award was given to the student ___.

who was nice
who demonstrated exceptional creativity and commitment throughout the year
that existed

The new park, ___, has become a popular community gathering space.

which is green
which replaced a former industrial site, has been planted with native species and
which is outside

She consulted a specialist ___ before making a final decision.

who was there
who had published extensively on the topic
that she liked
57

Relative Clauses in an Analytical Essay Paragraph

Write a formal analytical paragraph (6 to 8 sentences) about a topic you have studied. Use at least three relative clauses to add precision and detail. Aim for the kind of sentence complexity expected at secondary school level.

My topic:

My analytical paragraph:

Draw here

Relative clauses I used (list them):

62

Write Using All Five Relative Pronouns

Write a paragraph of 8 to 10 sentences on any topic. In your paragraph, use all five relative pronouns at least once: who, which, that, whose, where. Underline each relative pronoun.

My topic:

My paragraph:

Draw here

Which pronoun was hardest to use naturally? Why?

63

Sort: Sentence Complexity Level

Sort each sentence from least to most complex based on its use of relative clauses and other embedded information.

The dog barked.
The dog that lives next door barked all night.
The dog, which belongs to our neighbour who recently moved in, barked all night despite the cold.
She read.
She read the book that won the prize.
She read the book that won the Booker Prize, which is awarded annually to the best novel published in English.
Simple (no embedded clauses)
Moderate (one relative clause)
Complex (two or more embedded clauses)
65

Formal vs Informal: Which Relative Clause Form?

Circle the more formal version of each relative clause.

Which is more formal?

The person that I was talking to agreed.
The person to whom I was speaking agreed.

Which is more formal?

The policy which the council introduced was controversial.
The policy that the council brought in was controversial.

Which is more formal?

The researcher who wrote the report also led the study.
The researcher that did the report also ran the study.

Which is more formal for academic writing?

The issue which researchers have studied is complex.
The issue that researchers have looked at is complex.
66

Rewrite the Passage at Two Complexity Levels

Rewrite the passage below twice: once as a simple text (short sentences, no relative clauses) for a Year 2 reader, and once as a complex text (with relative clauses and embedded information) for a secondary school reader.

ORIGINAL PASSAGE: Migrating birds travel long distances. Some travel thousands of kilometres. They use the stars to navigate. They also use the Earth's magnetic field. Some species have been doing this for millions of years. Simple version (Year 2):

Draw here

Complex version (secondary level):

Draw here
TipThis exercise teaches your child to consciously match sentence complexity to audience — one of the most important writing skills there is.
68

Peer Review: Assess a Paragraph for Relative Clause Use

Read the paragraph below. Write a peer review commenting on: how well relative clauses are used, whether they are correctly punctuated, whether they add value, and any improvements you would suggest.

STUDENT PARAGRAPH: Australia, who has a population of about 26 million, is a large country. The country, that has many unique animals, is known for kangaroos and koalas. The Great Barrier Reef which is a coral reef is in Queensland. Scientists that study the reef say it is under threat from climate change, which is a big problem. Your peer review:

Draw here
70

Relative Clause Hunt and Build

Try these activities to practise relative clauses in everyday life.

  • 1Describe five objects in your house using a sentence that contains a defining relative clause for each. For example: 'The mug that has the blue handle belongs to Dad.'
  • 2Read a newspaper article and highlight every relative clause you can find. Classify each as defining or non-defining. Count which type is more common.
  • 3In conversation with a family member, try to use at least five relative clauses naturally. Ask your family member to count how many you used. Discuss whether they sounded natural or awkward.
72

Write a Profile Using Relative Clauses

Write a 12 to 15 sentence profile of a real or invented person — a scientist, artist, athlete or historical figure. Use at least six relative clauses of different types (defining, non-defining, with whose, where, and one reduced relative clause). Label each one in the margin.

Profile subject:

My profile:

Draw here

Relative clauses used (list them):

TipProfiles are excellent authentic writing contexts for relative clauses. If your child has a favourite historical figure or athlete, this task will feel personally meaningful.
73

Sort: Effect of Relative Clause Placement

Each sentence has the relative clause in a different position. Sort them from the version that flows most naturally to least naturally.

The explorer who had spent years in the Amazon finally published her findings.
The explorer finally published her findings who had spent years in the Amazon.
Her findings, which were published last year, changed how scientists understand the rainforest.
Her findings which changed how scientists understand the rainforest were published last year.
Flows most naturally
Acceptable but slightly awkward
Awkward or unclear
77

Write with Intentional Sentence Variety

Write a descriptive passage of 10 to 14 sentences about a natural or urban environment. Deliberately vary your sentence structures: use short sentences for impact, long sentences with relative clauses for detail, and at least one sentence that begins with a relative clause mid-structure. Mark each sentence type in the margin.

My setting:

My passage:

Draw here
TipReading the passage aloud is the best way to check sentence variety. If every sentence sounds the same length and rhythm, more variation is needed.
79

Advanced Relative Clause Selection

Circle the most precise and grammatically correct option for each formal sentence.

The report was written by the committee ___.

that oversees environmental policy
which oversees environmental policy
Both are correct in this context

The prime minister, ___, addressed the nation.

who had just returned from overseas
which had just returned from overseas
that had just returned from overseas

She cited the scientist ___ research changed the field.

that
whose
who

The year ___ the discovery was made was 1953.

when
where
which
81

Comparative Analysis: Relative Clause Use in Two Texts

Find one paragraph from a novel and one from a formal essay or report on the same topic. Analyse how each uses relative clauses: frequency, type, purpose and effect. Write a comparative analysis paragraph.

Novel source and paragraph:

Draw here

Essay/report source and paragraph:

Draw here

Comparative analysis — how does each text use relative clauses and why?

Draw here
TipComparative analysis is a secondary school skill that can be introduced effectively at upper primary. Keep the expectations realistic: look for patterns rather than exhaustive analysis.
84

Sort: Strong or Weak Use of Relative Clauses?

Sort each example based on whether the relative clause adds meaningful precision or is unnecessary.

The ocean, which is wet, covers most of the Earth.
Marie Curie, who was the first woman to win a Nobel Prize, changed the field of chemistry.
The park, which exists, is near our house.
The treaty, which was signed in 1648, ended the Thirty Years War.
She gave it to the person that was there.
She gave the award to the student whose work had shown the most remarkable improvement over the year.
Strong — adds genuine precision or detail
Weak — unnecessary or vague
85

Edit a Student Essay for Relative Clause Errors

This student paragraph has five errors involving relative clauses (wrong pronouns, missing or misplaced commas, dangling placement). Find all five, explain each error, and rewrite the corrected paragraph.

STUDENT PARAGRAPH: Frederick Douglass was an American leader who's autobiography became a classic. He escaped from slavery in 1838 which was a life-threatening act. The book, that he published in 1845, shocked readers with its vivid honesty. Douglass became a speaker who he inspired thousands. He met Abraham Lincoln, which was the President, twice during the Civil War. List the five errors and explain each:

Draw here

Corrected paragraph:

Draw here
87

Relative Clauses: Final Review (Set A)

Choose the best answer for each question.

Which sentence is grammatically correct?

The student who's work was chosen received a prize.
The student whose work was chosen received a prize.
The student which work was chosen received a prize.

Which sentence uses commas correctly?

Australia which is in the southern hemisphere, has a hot summer.
Australia, which is in the southern hemisphere, has a hot summer.
Australia, which is in the southern hemisphere has a hot summer.

Which sentence correctly omits the relative pronoun?

The song I heard last night was beautiful.
The singer who I heard last night was beautiful.
The song that was written last night I heard was beautiful.

Which sentence uses 'whom' correctly?

The author whom I admire most is Tim Winton.
The author who I admire most is Tim Winton.
Both are correct in informal writing
88

Reflection: Relative Clauses in My Writing

Choose a piece of your own writing from the past month. Analyse it for relative clause use and then revise it.

Title of my piece:

How many relative clauses did I use? List them:

Were they correctly punctuated? What errors did I find?

Revised version of one paragraph (improved using relative clauses):

Draw here
89

Extended Project: Relative Clauses Across Subjects

Investigate how relative clauses function in the academic writing of different subjects.

  • 1Choose a topic from science, history or geography. Write three different paragraphs about it — one using no relative clauses, one using three defining relative clauses, and one using three non-defining relative clauses. Compare how each version reads and discuss with a family member which version is most appropriate for an academic report.
  • 2Find an academic article or textbook chapter on a topic you have studied this year. Count the relative clauses in three consecutive paragraphs. Are more of them defining or non-defining? What does this tell you about academic writing conventions?
  • 3Create a reference card titled 'Relative Clauses at a Glance' that summarises the key rules, gives examples of each type, and lists two common errors to avoid. Keep it in your writing folder.
93

Write a Research Summary Using Relative Clauses

Choose a topic you have researched this year. Write a 10 to 12 sentence research summary. Include at least five relative clauses of different types. Your summary should be accurate, formally written and demonstrate full control of relative clause punctuation.

Research topic:

My research summary:

Draw here
TipA research summary is an authentic academic writing task. If your child has recently completed a topic in history, science or geography, this is the ideal moment to write a polished summary of what they have learned.
94

Choose the Most Effective Sentence

Read each set of options. Circle the sentence that uses a relative clause most effectively for the given purpose.

Purpose: to write a formal biography opening.

Nelson Mandela was a person who was very important.
Nelson Mandela, who spent 27 years in prison before becoming South Africa's first democratically elected president, is one of the 20th century's most significant figures.
Nelson Mandela did important things.

Purpose: to write a scientific definition.

A volcano is a hole in the ground.
A volcano is a geological formation where molten rock from the Earth's mantle erupts through the surface.
A volcano that is dangerous erupts.

Purpose: to write an engaging story opening.

There was a house on a hill.
At the end of the lane stood a house whose windows seemed to watch the road below.
A house that was there had windows.
96

Create a Relative Clause Teaching Poster

Create a teaching poster that explains relative clauses to a Year 3 student. Your poster should include: a clear definition, examples of defining and non-defining clauses, the rules for when to use commas, and at least three examples from real published texts.

Rough draft of my teaching poster (plan the layout and content here):

Draw here
TipCreating a teaching resource requires the deepest level of understanding — your child must explain clearly, simply and accurately. Display the finished poster in your learning space.
98

Relative Clause Mastery Project

Complete this two-week mastery project to consolidate your relative clause skills.

  • 1Week 1 — Collection: Collect 10 sentences containing relative clauses from published texts (novels, newspapers, textbooks). Classify each as defining or non-defining, identify the relative pronoun used, and rate the sentence as 'simple', 'moderate' or 'complex'. Display your collection with annotations.
  • 2Week 2 — Production: Write an original piece of at least 20 sentences on any topic of your choice. Deliberately include at least eight relative clauses using a variety of pronouns and clause types. Colour-code them in the finished piece (different colours for defining vs non-defining).
  • 3Reflection: Write a half-page personal reflection answering: What did I learn about relative clauses this week? What was hardest? How will I use relative clauses more intentionally in my future writing?
99

Reflection: Relative Clauses and My Voice as a Writer

Reflect carefully on what you have learned about relative clauses through this worksheet.

Which type of relative clause (defining or non-defining) do you find most useful in your own writing? Why?

What was the most challenging concept to master? How did you work through it?

How will you use relative clauses differently in your writing from now on?

Name one text type where relative clauses are especially important and explain why.