How to Write Complex Sentences


Today I want to show you how to write Complex Sentences for your IELTS Writing Task 1 and Task 2.

Don’t worry, making a “complex sentence” isn’t really complex or difficult. But, knowing how to write a great sentence is very important so you can get a high score on the grammar criteria on your IELTS writing test.

In the lesson I will show you some examples of complex sentences, and I’ll give you some very important warnings about using them! Finally I’ll show you how to write one, then we’ll get some practice.

Let’s go.


What are Complex Sentences?


A complex sentence is a sentence containing more than one idea, like this one:

“The number of young people under 14 is projected to go down, while the number of people aged 60+ will nearly double during the same period.”

This sentence contains two ideas:

1. The number of young people will go down

2. The number of 60+ people will double during the same period

Here’s another one:

“Due to the worldwide prevalence of English, some young people in China have lost interest in learning old Chinese language and characters, and have therefore lost an important tradition.”

This sentence has three ideas:

1. A cause (due to the worldwide prevalence of English)

2. An effect (young people have lost interest in learning old Chinese language)

3. A further result (they have therefore lost an important tradition)


Why do I need to make Complex Sentences?


Being able to use occasional complex sentences in your writing is actually a part of your Grammar Criteria, which is worth 25% of your writing score.

Take a look at the IELTS Writing Grammar Criteria for scoring band 6 and 7:

ielts writing grammar criteria band 6 band 7

Notice that it says “a mix of simple and complex forms”, and “a variety”, as well as “error-free”. All of this is really important.

With this in mind, before we learn how to write complex sentences I want to give you some important warnings.


Important Warnings about Using Complex Sentences:

A very common problem with IELTS writers is that they think they need to be really fancy and try to impress the examiner. This usually results in people using grammar and vocabulary that is unfamiliar or too difficult, and a lot of mistakes.

“-Produces frequent error-free sentences”

Producing a lot of errors will hurt your band score much more than fancy complicated sentences will help it! You don’t need to be fancy when you write. You should be simple when you write, and only use grammar and vocabulary that you understand well.

Here is an example of a sentence that an IELTS writer wrote for a Task 2 question about overpopulation. She was trying to be too fancy:

“The problem of overpopulation is a common one today in which the consequences are becoming more serious as less available resources and housing, though mainly it is affecting developing countries with high birthrates.”

This sentence is too complicated. The writer is trying too hard to impress here, and she has created a long and incoherent sentence with grammar errors. Sentences like this will hurt your Grammar score, and your Cohesion/Coherence score.

Her sentence is trying to express four different ideas, which is too many. Now, on the other hand, if we rewrite this as four separate sentences, it is too simple:

“Overpopulation is a common problem today. Its consequences are becoming more and more serious. The consequences are less available resources and housing. This problem mainly affects developing countries with high birthrates.”

This is not going to get a very good score either. We need to find a balance. Not every sentence has to be complex!

"-Uses a mix of simple and complex sentence forms"

Let’s improve it:

“Overpopulation is a common problem today. Its consequences include less available resources and housing, and they are becoming more serious each day. However, this problem mainly affects developing countries which have high birthrates.”


This final example is much better. It uses a simple sentence, a complex (two ideas) sentence, then another simple sentence.


So, let’s summarize the advice:

  • Only use grammar and vocabulary that you are familiar with! Be simple.
  • Don’t try to include more than 3 ideas in one sentence, unless you are very confident doing this!
  • Don’t make every sentence in a paragraph complex! An excellent paragraph should have a mix of simple sentences and complex ones.


So… How Do I Make a Complex Sentence?


Basically, to make a complex sentence you need to combine two or three ideas into a single sentence. There are a number of different ways to do this:

  • Using adjective clauses (also called relative clauses)
  • Using noun clauses
  • Creating compound sentences with conjunctions


The rest of our lesson will focus on creating compound sentences with conjunctions, because that is really the simplest and best way to make complex sentences. (If you want more information about adjective and noun clauses, then you should look these up later! They can be useful, but don’t worry about them for now.)


What is a Compound Sentence?

A compound sentence is just a simple sentence connected to another simple sentence, using a conjunction (a linking word). These conjunctions are used to show a relationship between the two sentences or ideas.

“These minutes began at just over 70 million, and rose sharply until 1998.”

Although international calling remained higher in total minutes, fixed line and national calling both had similar usage numbers.”

“If governments do not do something to restrict industrial pollution, then global warming will get worse.” (note, you can leave out then)

Compound sentences are a really simple way to make great sentences on your IELTS Writing test! You should try to become familiar with using many different conjunctions.


Common conjunctions (linking words):

And / also / but / although / because / so / if

Common conjunctions, grouped by their purpose:

[add information]    and / as well as

[show contrast]    but / although / even though / despite / while

*While is often used as ‘lighter’ contrast than the rest.

[introduce a reason/cause]    because (of) / due to / since

[introduce an result/effect]    so / and consequently, / and as a result,

[introduce an example]    such as / like

[introduce a condition]    if __ then __

  • Note that all of these conjunctions require specific grammar knowledge to use! We won't discuss the grammar here, so if you are unsure how to use any of these, just search the internet for "conjunction + (the specific word)" and you will find plenty of exercises.
  • Note that some “linking words” are called transitions, because they do not link sentences or ideas, but instead begin new sentences.

Some common transitions include: however / on the other hand / additionally / furthermore / for example / firstly / finally.

Transitions will not help you to make complex sentences, but they are excellent ways to show your reader (examiner) the relationship between your sentences, and increase your Cohesion/Coherence score.


Let’s Get Some Practice.


Let’s get some practice with creating complex sentences.

By the way, it is really good practice to write out example sentences on to a piece of paper (or type them out on a computer); it can help you get a feeling for the right kind of grammar and rhythm of a great sentence. If you have some time and want some really good practice, you should try it with the questions below.

Let’s Get More Practice!

Take a look at the Task 2 essay below. This is a band 9 essay! I want you to identify all of the conjunctions, and notice the mixture of complex and simple sentences used.