Academic Writing Task 1 · Lesson 4 of 7
Describing diagrams and processes
Some Task 1 questions show how something works or how something happens. Learn the grammar you need to explain purpose, cause and result, and to add extra information.
In this lesson you will
- read a model description of a diagram and label its parts
- use language for showing purpose (to, in order to, so as to, so that)
- use language for showing cause and result (because, due to, as a result…)
- use relative clauses to give extra information
Part A
How a hydraulic lift works
Task: The diagram below shows the basic operation of a hydraulic lift. Summarise the information by selecting and reporting the main features, and make comparisons where relevant. Write at least 150 words. (About 20 minutes.)
Read this description of the diagram.
The diagram shows how a hydraulic lift works. The system is quite simple. It consists of the lift carriage, where passengers stand, which is connected to a piston that raises and lowers the carriage, and a tank that holds hydraulic fluid.
When a passenger presses the ‘up’ button to raise the lift, an electric signal is sent through electrical wires to a pump. This causes the pump to move fluid from the tank into the bottom of the piston housing so as to force the piston up. As the piston housing fills with fluid, the piston is raised higher. The lift carriage, which is attached to the top of the piston, is also forced up. The blue arrows show the direction in which the hydraulic fluid flows.
When the passenger presses the ‘down’ button, another electric signal is sent so that the pump is switched off. At the same time, a signal is sent to a valve just in front of the pump in order to shut off the flow of fluid from the tank to the piston housing. In its new position, the valve allows hydraulic fluid to flow from the piston housing back into the tank. This reverse flow is shown by the red arrows. The piston and the lift carriage attached to it are then brought back down by the force of gravity.
Label the diagram
Use the words in bold in the description to label parts A to I of the diagram. F has been done for you.
- A
- B
- C
- D
- E
- F
- lift carriage
- G
- H
- I
Language for showing purpose
Look at the four underlined phrases in the description. They all explain why something happens: its purpose. Use these structures when you describe a diagram.
| Structure | Example |
|---|---|
| to + infinitive | The passenger presses the ‘up’ button to raise the lift. |
| in order to + infinitive | A signal is sent to a valve in order to shut off the flow of fluid. |
| so as to + infinitive | Fluid moves into the piston housing so as to force the piston up. |
| so that + full clause | A signal is sent so that the pump is switched off. |
Choose the best option
Choose the option that correctly completes each sentence.
- The water is boiled ______ kill harmful germs.
- Scales are used ______ the ingredients are weighed accurately.
- There is a battery ______ provide electrical power.
- ______ grow straight, the plant needs to be supported with a piece of wood.
- The leaves need to be left in the sun ______ dry thoroughly.
- The frame is made of aluminium ______ the structure is light but strong.
To, in order to and so as to are followed by an infinitive (a verb). So that is followed by a full clause with its own subject and verb (the structure is light). In order and so as are never used without to.
Part B
Cause and result
Process diagrams often show one thing causing another. Study the stages below, which show how stalactites form on the roof of a cave. What cause and result relationships can you see?
- Water seeps in. Water seeps through cracks and holes in the limestone rock and absorbs calcium carbonate. Drops of solution form on the cave roof.
- A ring forms. Each drop that falls leaves behind a ring-shaped deposit of calcite.
- A “soda straw” grows. The rings build up into a thin calcite tube called a soda straw.
- The stalactite forms. The straw becomes blocked by a stone or soil, so the solution flows down the outside and a stalactite forms around the straw.
Words and phrases for expressing cause and result include because, because of, due to, results in and as a result.
Complete the description
Type a word or phrase from the box into each gap. Use each one once.
- as a result
- because
- causes
- consequently
- due
- give rise to
- on account of
- results in
Water leaks slowly into the cave there are thousands of tiny cracks and holes in the limestone rock. On its way down, the water absorbs the calcium carbonate in the rock, and this a mineral solution. Small drops of this solution form on the roof of the cave. When each drop falls, it leaves behind a ring-shaped deposit of calcite. This process is repeated many times and, , a thin calcite tube is formed. This tube is sometimes called a soda straw its shape. Occasionally, the soda straw gets blocked to a piece of stone or soil. This the drops of solution to pour down the outside of the straw. , calcite deposits build up around the straw, and these the typical cone shape of the stalactite. Only the straws that get blocked will eventually become stalactites.
Gaps 3 and 7 can be either as a result or consequently. Because is followed by a clause (subject + verb). On account of, because of and due to are followed by a noun phrase.
Part C
Adding extra information with relative clauses
Relative clauses add information about a noun. They help you combine short sentences into longer, more complex ones, which improves your Grammatical Range and Accuracy score.
| Type | Example | Rules |
|---|---|---|
| Non-defining (extra information) |
The lift carriage, which is attached to the top of the piston, is also forced up. | The sentence still makes sense without the clause. Use commas. Do not use that. |
| Defining (essential information) |
Only the straws that get blocked will eventually become stalactites. | The sentence doesn't make sense without the clause. No commas. You can use that, which, who, where. |
Combine the sentences
Join the information into one sentence using a relative clause (defining or non-defining). Watch your commas!
Example: There is a light. It turns on when the temperature rises. → There is a light which turns on when the temperature rises.
- A container. It's made of steel. It catches the rain water.
- Chlorine is added to the tank. It kills any dangerous bacteria.
- The pages pass through a machine. It cuts off the edges.
- The programming takes six months. It is done in India.
- The mixture is heated to a temperature. The temperature causes a chemical reaction.
- A container, which is made of steel, catches the rain water.
- Chlorine, which kills any dangerous bacteria, is added to the tank.
- The pages pass through a machine that cuts off the edges.
- The programming, which takes six months, is done in India. or The programming, which is done in India, takes six months.
- The mixture is heated to a temperature which causes a chemical reaction.
If your answer was marked wrong, compare it carefully with the model. Check your commas and your relative pronoun. A different but correct sentence may not be recognised automatically.
Band descriptors
What the examiner looks for in your grammar
Here is a summary of Grammatical Range and Accuracy at Bands 6 to 8. Notice how range and flexibility increase at each band.
| Band | Grammatical Range and Accuracy (summary) |
|---|---|
| 8 | A wide range of structures is used flexibly and accurately. Most sentences are error-free, and punctuation is well managed. Occasional mistakes have very little effect on communication. |
| 7 | A variety of complex structures is used with some flexibility and accuracy. Grammar and punctuation are generally well controlled, and error-free sentences are frequent. |
| 6 | A mix of simple and complex sentences is used, but with limited flexibility. Complex structures are less accurate than simple ones. Errors occur but rarely make the meaning unclear. |
Summarised from the IELTS Writing Band Descriptors. Download the full descriptors (PDF).
Write the full answer
Now write a complete answer to the hydraulic lift task at the top of this lesson, in your own words. Use at least two purpose phrases, one cause and result phrase, and one relative clause. Aim for at least 150 words in about 20 minutes.
- Did you introduce the diagram in your own words, without copying the task?
- Did you include an overview (for example, that the lift is raised by pumping fluid into the piston housing, and lowered by gravity when the fluid flows back)?
- Did you describe the upward and downward movements in a logical order?
- Did you use purpose phrases (to, in order to, so as to, so that), cause and result language, and relative clauses?
- Did you write at least 150 words?
Activities adapted from British Council IELTS teaching materials (takeielts.britishcouncil.org).