KS3 grammar: sentences and clauses


Sentences and Clauses – introduction

There are four types of sentence:


Simple Compound Complex Minor

A clause is a group of words which acts as a single unit and is built round a verb, for example:

he lives in AmericaCompound and complex sentences contain two or more clauses:


John is living in America.


He lives in America, but his family is still in Wales.


While his family is still in Wales, John’s staying with friends.

Minor: A minor sentence is one without a verb, e.g:

First, a word about sentences.

America, of all places!

To produce varied, interesting writing with effective changes in rhythm, pupils need to be able to use a variety of sentence types. They need to learn to exploit the opportunities that different clause types and clause combinations can offer.

Sentence and clause elements and their functions

Simple sentences and main clauses almost always have a subject and a verb, and sometimes have an object:




noun phrase

(or a verb chain)



noun phrase

The tall girl

was kicking

her desk.

The baby


More complex clauses may also have:


Adverb phrases

Preposition phrases

Noun phrases

Adverbial clauses

a complementNoun


Noun phrase


Adjective phrase

Prepositional phrase


which ‘completes’ the verb

an indirect objectNoun


Noun phrase

which stands between the verb and the main object

It rains in the winter.

Joe left this morning.

He felt quite ill

He was in a bad mood, or at least he seemed it.

Mum gave him a tablet.

He would never lend his son his car.

Verbs as heads of clauses

The verb is the most important word in the sentence because it is essential, whereas the subject may sometimes be missed out (for example, in imperatives):


Come in!

In some languages, the subject can always be omitted; in Latin, for example, the verb dormio means “I sleep”, and dormit means “He sleeps” or “She sleeps”. These words can be used as complete sentences. The same is true of most of the languages derived from Latin (e.g. Spanish and Italian), and many other languages.

In English, as in other languages, the rest of the sentence may be seen as an expansion of the verb. If the verb is won, we know that the sentence is about an incident in which someone won something. Each of the other elements in the sentence answers some question about the verb:

Who won? She won.

What did she win? She won the first race.

When did she win? She won yesterday.

How did she win? She won by cheating.

This is just like the relation between a phrase and its head; for example:

her victory in the first race

Here the head word is victory and the words her and in the first race modify its meaning by answering the questions “whose victory?” and “victory in which event?”. The verb is therefore the head of its clause, so it stands at the top of structure diagrams:



Some of the simplest sentences and clauses consist of a verb and a noun, a pronoun or a noun phrase acting as the verb’s subject. The subject normally stands just before the verb.

The girl with brown hair
Moving my arm

Verbs and verb chains

The verb may be expanded into a chain of one or more auxiliary verbs followed by a main verb.





has forgotten.


may have forgotten.

The little rabbit with floppy ears

has been running.

Raising your arm

may hurt.

Each verb in the chain is tightly connected to the verbs on either side, just like links in a chain. See how forgot changes to forgotten when it follows has, and has changes to have after may. This is because each verb in the chain decides the form of the next verb:

auxiliary verb
form of next verb
have (has, had)
past participle (e.g. been, forgotten)
be (is, are, was, etc.)
present participle (e.g. running)
may (might)
infinitive (e.g. have, hurt)

We can show these verb-verb bonds like links in a chain:


The verb – or the last verb in a chain – may be accompanied by a second noun, pronoun or noun phrase or clause. This is the verb’s object, which normally follows the verb.

Indirect object

Sometimes a third noun, pronoun or noun phrase stands immediately between the verb and the object. This is called the indirect object (because the action affects it less directly than it affects the ordinary, or ‘direct’, object). It’s convenient to abbreviate these labels, so s = subject, o = (direct) object, i = indirect object.


Some verbs, for example be, seem appear, get, become, sometimes need their basic meaning to be completed. This ‘complement‘ (c) which ‘completes’ the verb normally follows both the verb and the object (if there is one).


Many elements can modify the verb’s meaning by adding information about time, place, manner etc. Such elements are called adverbials (a)because this is the main role of adverbs. Adverbials are not fixed to one position but move fairly freely: they can be at the start (a1), in the middle (a2) or at the end (a3).

Notice how adverbs can split the verb chain, so will be becomes will probably not be.

Variations on the basic pattern of clause elements

We can, and often do, vary the basic pattern and you should be aware of these alternatives:

Variations according to purpose

The elements affected by these variations are the subject and the verb.

  • The simplest clause form is called the declarative. Here the subject is before the verb as in all the earlier examples:

You are my friend.

  • ‘Yes/no’ interrogative (expecting the answer ‘yes’ or ‘no’). Here the subject follows the first verb, which must be an auxiliary verb:

Have you seen it?

Did you see that?

Are you my friend?


  • how this change in the position of the subject splits the verb chain.
  • how this rule shows that be is always an ‘auxiliary’ verb even when it is not followed by another verb. For more on this, click here.


  • ‘Wh’ interrogative (introduced by an interrogative word spelt wh…). Here too the subject follows the first auxiliary verb, unless it is itself the interrogative word.

Who are you meeting?

Who is your friend?

When shall we meet?

Why did you do it?

  • Exclamative. Here too there is a ‘wh-word’ at the beginning, but the subject is in its normal position before the verb.

What a friend you are!

What a shame!

How tall you are now.

  • Imperative. Here the subject is usually hidden, but would otherwise be you; and the first verb is in its basic form without any ending:

Be my friend!

Please be my friend.

Take 3 eggs. Whisk them in a large bowl.

  • And whatever the purpose, a clause can also be negative, with either not or n’t right after the first auxiliary verb:

You are not my friend.

Aren’t you my friend?

Why aren’t you my friend?

Don’t touch it!

KS3 pupils use all these variations in speech, but they may need to be encouraged to use them more freely in their writing.



Many verbs can be either active or passive, a contrast which is traditionally called ‘voice’.

Active: Sam built this house.

Passive: This house was built by Sam.

The information is the same but the focus is different.

The first sentence is about what Sam did, so Sam is the subject of the active verb. The second sentence is about the house, and the house is the subject of the passive verb.

  • Passive verbs have a different form (was built) from active verbs – see below.
  • The active verb’s object (the house) is the passive verb’s subject.
  • The active verb’s subject (Sam) may be omitted in the passive, or may be included with by.

See below for how to choose between active and passive clauses.

“Who done it?”

In an active clause the “doer” or agent is always clear:

Moriati shot the stranger.But in a passive clause it is possible not to reveal “who done it”:

The stranger has been shot.Or a doer can be identified using by :

The stranger has been shot by Dr Watson. 

The passive form is the same as the past participle, and is often combined with the auxiliary be:

We saw it It was seen
I have mended it It has been mended
We must finish it It must be finished
David is painting it It is being painted by David

Sometimes we use get instead of be:

He got arrested.

When should the passive form be used?

( … or perhaps, “when should you use the passive form?”)


The thief was spotted by the policeman.

It is considered to be a good thing.The official photographs will be taken by Josh.

The passive voice can sometimes sound pompous and impersonal.

Using the passive

Word processing software that includes grammar checking usually “corrects” any use of the passive and suggests the active alternative. Most people agree that the passive should be avoided unless there is a particular reason to use it.

When to use the passive

  • In order to leave the actor unspecified, perhaps because we don’t know ‘who done it’, or don’t want to say, or because the actor remains to be decided.

A report should be written …Application forms must be returned.

I have been told about these rumours.


  • To focus attention on the actor, by adding the by phrase, normally at the end of the clause.

    The best essay was written by the youngest pupil.

    It was broken by vandals.

  • To change the position of the natural subject and object, in order to link back to what has gone before.

    Q. Who ordered pizza and who wanted pasta?

    A. The pizza was definitely ordered by John. I’m not sure about the pasta.

Many schools still prefer pupils to write science reports in the passive voice.

The substance was put into a test tube, which was held with forceps over a bunsen burner until a red glow was observed. 

Clause types

Main clauses

A main clause is complete on its own. It may be a complete sentence written with a capital letter and full stop (or ?!):

Alice saw a rabbit.

Anna is eating her favourite supper.

Finally, we arrived.

Simple sentences consist of just one main clause:

Hannah is eating her favourite supper.

Finally, we arrived.

Compound sentences consist of two or more main clauses – clauses of equal weight, joined together by and, or, but, or so. (This relationship is called co-ordination, and is explained in a separate unit.)

I’ve lost my school bag but the keys are here so I’m not locked out.

It’s late, so she’s not going.

I like reading and I love Hemingway.

Complex sentences contain one or more subordinate clauses.

Subordinate clauses

A subordinate clause is part of a larger clause.

He burns easily if he doesn’t use sun cream.

Where is the cup of tea that you promised to make?

Everything she buys is really expensive.

The class I taught last year all did quite well.

Because the subordinate clause is part of the larger clause, the remainder of this clause is not itself a complete clause; so in the first example above the main clause is the entire sentence, not He burns easily. For more on this idea click here.

Using subordinate clauses allows writers to vary pace and rhythm and to indicate the relative importance of different ideas.

To learn more about subordinate clauses, click any of the following links:

Subordination signals

You can usually recognise subordinate clauses easily because they are signalled:

  • by a non-finite verb which is the clause’s first or only verb:

    We ate early, being excessively hungry.

    To be ready in time, he did without supper.

    Having eaten early, we watched the news.

    We helped unpack the tent.

  • or by a subordinating word:

    They sat there until it started to rain.

    He’s the one who started it.

    After he arrived things started to happen.

    They will walk out unless we give in to them.

However, some subordinate clauses have no signal at all, because the subordinating word – which is always that – is omitted. They are harder to recognise, but can nearly always be identified by replacing the missing that:

I know you are hiding something. (… know that you are …)

Who says I am a coward? (… says that I am …)

That man she likes is very tall. (… man that she likes …)

The book I’m reading won a prize. (… book that I’m reading …)

This is a common feature of writing at KS3, and pupils need to understand and be able to handle it.

Finite and non-finite clauses

    • Finite clauses have a finite verb as their head.

I know everyone sent their friends birthday cards this year.

  • Non-finite clauses have a non-finite verb (i.e. an infinitive or a participle) as their head.

    Everyone promised to send their friends birthday cards this year.

This important difference is always signalled by the first verb in the verb-chain:

I know everyone has sent their friends birthday cards this year.

Everyone hopes to have finished their projects by the end of the week.

Having already finished their projects, they can have a rest.

This difference also affects the ways in which these clauses can be used:

    • Finite clauses may generally be used as complete sentences (once any subordinating words have been removed):

Everyone sent their friends birthday cards this year.

  • Non-finite clauses are always part of a larger clause:

    They have made plans to send their friends birthday cards this year.

This is because the use of a non-finite verb such as to send is one of the main signals that a clause is a subordinate clause.

This difference may also affect the meaning of sentences, often in a subtle way. For example, compare:

  • I remembered that I was responsible. (finite)
  • I remembered to do it. (non-finite)
  • I saw that you did it. (finite)
  • I saw you do it. (non-finite)

These highlighted clauses are non-finite:

We really enjoy sailing our dinghy.

Spurred on by the crowd, they won the match.

He struggled to read the small type.

Changing the tense of the sentence doesn’t change the non-finite clause:

  • We enjoyed sailing our dinghy.
  • We will enjoy sailing our dinghy.
  • He struggles to read the small type.
  • He will struggle to read the small type.
  • Spurred on by the crowd, they won the match.
  • Spurred on by the crowd, they are winning the match.

Noun clauses

Noun clauses, like nouns, pronouns and noun phrases, can act as:

  • the object of a verb:
I know that Mary bought the dog.
  • the subject of a verb:
Why she bought it is a great mystery to us all.
  • the object of a preposition:
Don’t judge her by what she buys.
  • a complement
She seems to be pleased with it.

If a clause fulfils the role of a noun in a sentence, it is a noun clause.

At Key Stage 3, pupils should be developing the use of expressions like these, where a noun phrase is followed by a noun clause:

We discussed the idea that she had bought a cat.We discussed the fact that she had bought a cat.

We discussed the possibility that she had bought a cat.

This structure is a useful tool to help thinking skills because it involves important distinctions about the logical status of information – e.g. as facts, beliefs, suggestions, theories, and ideas.

Relative clauses

Relative clauses are adjectival because, like adjectives, they modify a nouns; but unlike adjectives, they come after the modified noun:

Sam is the one who usually sits here.

The shop where I work is closing.

This computer, which I usually use, is faster.

Relative clauses usually start with a relative pronoun:

that, who, which, whom, whose

or a relative adverb:

when, where

Relative pronouns and relative adverbs act as subordinating words – they signal a subordinate clause.

Using relative clauses allows KS3 writers to progress from co-ordination, producing more varied and digestible prose:

Joe bought a dog and the dog barks all night and it keeps us awake. Co-ordinated main clauses
The dog that Joe bought barks all night and keeps us awake. Relative subordinate clause

Sometimes, the relative pronoun can be left out, but sometimes it can’t. Click here for details.

Adverbial Clauses

An adverbial subordinate clause modifies the meaning of the main clause in much the same way as an adverb:

  • Although I regret it, I must decline your invitation. (adverbial clause)
  • Regrettably, I must decline your invitation. (adverb)
  • They arrived before it started raining. (adverbial clause)
  • They arrived promptly. (adverb)

Here are the main relationships expressed by adverbial subordinate clauses:

Time after, as, as soon as, before, once, since, until, when and whenever, while
Place where, wherever
Reason as, because, since
Comparison as, as if, as though, than
Condition as long as, if, in case, provided, provided that
Negative condition if … not, unless
Concession although, as long as, even if, even though, though, whereas, while
Purpose to, in order to, so that
Result so that, so … that, such … that

Notice that some of these words (those shown in bold) can be used to signal more than one relationship.

Clauses within clauses

A subordinate clause can be at the beginning, in the middle, or at the end of a sentence:

While he was paying for his petrol, his car was stolen.The teacher who has this group is away today.


His car was stolen while he was paying for his petrol.

Sentences can contain more than one subordinate clause:

While we were away, the girl who was looking after our cat heard that her grandmother had died.

Some of these clauses can be ‘nested‘ one inside another, like Russian dolls or Chinese boxes. For example,

He said that his father went to America because Kate is there.

contains the clause:

(that) his father went to America because Kate is there.

which in turn contains the clause:

because Kate is there.

Pupils can learn how to show nested subordinate clauses in a sentence:

  • by underlining:


  • or using “Chinese boxes”:

Non-finite verbs

Here is a refresher on non-finite verbs; for more explanation click here.

Non-finite verbs:

  • present participle: sailing

    I was sailing (was is finite, sailing is non-finite)

  • past participle: sailed

    They have sailed (have is finite, sailed is non-finite)

  • infinitive: to sail, sail

    I learned to sail (learned is finite, sail is non-finite)

    Watch him sail (watch is finite, sail is non-finite)

Subordinating words

subordinating conjunctions:

after, although, as, as if, as long as, as soon as, as though, because, before, if , in case, in order to, in that, once, provided (that), since, so that, than, that, though, until, unless, when, whenever, where, wherever, whereas, while … and others.relative or interrogative pronouns or adverbs

how, that, what, when, where, which, who, whom, whose, why; however, whatever … and others.


When can a relative pronoun (that) be omitted?

The computer I use at home is faster. The computer crashed is outside. X
The lesson I like most is English. The lesson follows this is English. X
The Alice I know has red hair. The Alice usually sits next to me is his sister. X
The bullet he saw was silver. The bullet killed him was silver. X

When the noun that the clause refers to is the object of the relative clause and the relative pronoun would have been that, this pronoun can be omitted; but in Standard English it cannot be omitted if it is the relative clause’s subject.

What’s left when you remove the subordinate clause?

Look at this sentence:


He burns easily if he doesn’t use sun cream.

This is a main clause, which contains a subordinate clause:

if he doesn’t use sun cream

The meaning intended by the writer or speaker is conveyed by the whole main clause. One part of this main clause is the subordinate clause if he doesn’t use sun cream.

But the remainder “He burns easily” is not a clause on its own; it is part of the whole main clause: He burns easily if he doesn’t use sun cream.

Of course the words he burns easily could stand alone as a main clause in a different sentence, or context, if they conveyed the writer’s full meaning; but in some cases the main clause is grammatically incomplete if we remove the subordinate clause. For example:

He said that it was too late. (Remainder: He said.)

Why he did it is unclear. (Remainder: Is unclear.)



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