Academic Writing Task 1 · mixed chart

Diagrams illustrating the design and placement of wave-energy machines

The diagrams below show the design of a wave-energy machine and its location.

Summarise the information by selecting and reporting the main features, and make comparisons where relevant. Write at least 150 words.

A wave-energy machine
  1. 1.Wave enters the chamber
  2. 2.Water level rises and falls
  3. 3.Air is pushed through the turbine
  4. 4.Turbine spins to drive electricity generator
Wave-energy machines: location options

Location options

  • Deep water location with large waves and high output has high installation costs
  • Shallow water location with small waves and low output has low installation costs

Chart redrawn by BandLadder from the data in the original IELTS practice task. Many IELTS practice tasks come from the Cambridge IELTS series (Cambridge University Press & Assessment); all rights in the original tasks remain with their owners.

Band 8 sample answer

The provided diagrams illustrate the operational mechanism of a wave-energy machine and compare two potential installation sites based on wave intensity and cost.

Overall, the machine generates electricity by converting the vertical movement of water into airflow that drives a turbine. Furthermore, there is a clear correlation between the location of the machine, the size of the waves, and the associated financial investment required for installation.

The first diagram depicts the internal structure of the device. As waves enter the chamber, the rising and falling water levels force air through a turbine located in the upper section. This airflow causes the turbine to rotate, which in turn powers an electricity generator. The design allows for continuous air movement regardless of whether the water level is rising or falling within the chambers.

The second diagram highlights two location options. Placing the machine in deeper water where waves are large results in a high energy output, but this is offset by high installation costs. Conversely, installing the machine in shallower water where waves are smaller leads to a lower energy output, yet this option is more economical due to lower installation costs.

190 words. Every figure in the answer comes from the chart above.

How to write about mixed charts

mechanism
a system of parts working together in a machine
correlation
a mutual relationship or connection between two things
offset
to counteract something by having an opposite effect
conversely
introducing a statement that reverses a previous one
economical
giving good value or service in relation to cost
depicts
shows or represents by a drawing or diagram

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Frequently asked questions

What should the overview say?

The diagrams illustrate that the machine functions by using wave-driven air to power a turbine, while its location choice involves a trade-off between energy output and installation costs.

How long should an IELTS Task 1 answer be?

At least 150 words; 170 to 200 is the safe range. Spend about 20 minutes on it and leave 40 for Task 2, which carries twice the marks.

How do I describe mixed charts?

Write one overview sentence that links the two visuals. Give each visual its own detail paragraph. Point out where one chart explains the other.

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