The diagram below shows how electricity is generated in a hydroelectric power station.
Sample Response
The diagram outlines the process of electricity production in a hydroelectric power station. The process begins when the water flows from the river into a high-level reservoir and ends with the transmission of electricity to the national grid. In general, the process is broadly distributed into day and night stages with the daylight stages involving electricity production from a river and storage of water in a reservoir. At night, the water flows back in the opposite direction towards an initial reservoir and the river. The day stage of the process involves channelling the river water into a high-level reservoir backed up by a dam. There is an intake area leading to the power station that opens during the day and closes at night. Water flows during the day to generate electricity through the power station turbines. The generated electricity is then sent to a national grid through power lines while the excess water runs to a low-level reservoir. During the night stage, the water stored in the low-level reservoir is reverted to the power station and the turbines of the generator pump it back into the high-level reservoir which is closed during the night. The river water is stored at the upper level and later it flows down, starting the cycle again.
IELTS Writing Correction
- 1. Remove unnecessary article Original: when the water flows Suggested revision: when water flows Why it matters: Water is used uncountably when describing the process in general.
- 2. Show the cycle Original: ends with Suggested revision: includes Why it matters: The diagram is cyclical, so transmission to the grid is not the final stage.
- 3. Use process wording Original: broadly distributed Suggested revision: broadly divided Why it matters: A process is divided into stages rather than distributed into them.
- 4. Use singular stage Original: daylight stages Suggested revision: daytime stage Why it matters: The overview contrasts one daytime stage with one nighttime stage.
- 5. Clarify energy source Original: electricity production from a river Suggested revision: electricity generation using descending water Why it matters: The diagram shows water driving turbines rather than electricity being produced directly from a river.
- 6. Name the reservoir Original: storage of water in a reservoir Suggested revision: storage of discharged water in the low-level reservoir Why it matters: During the daytime stage, water collects specifically in the low-level reservoir.
- 7. Use parallel label Original: The day stage Suggested revision: The daytime stage Why it matters: Daytime matches the later label nighttime more naturally.
- 8. Improve dam wording Original: backed up by a dam Suggested revision: held back by a dam Why it matters: Held back is the natural expression for water retained by a dam.
- 9. Use diagram term Original: intake area Suggested revision: intake Why it matters: The labelled component is the intake, not a broader area.
- 10. Identify turbine type Original: power station turbines Suggested revision: reversible turbines Why it matters: The diagram identifies turbines whose function changes between day and night.
- 11. Use definite article Original: a national grid Suggested revision: the national grid Why it matters: The diagram refers to the specific national grid shown.
- 12. Avoid unsupported detail Original: excess water Suggested revision: the water Why it matters: The visual shows the process water entering the lower reservoir, not merely excess water.
Suggested Rewrites
- when the water flows when water flows
- ends with includes
- broadly distributed broadly divided
- daylight stages daytime stage
- electricity production from a river electricity generation using descending water
- storage of water in a reservoir storage of discharged water in the low-level reservoir
Why this response received Band 7.5
The response explains the daytime generation and nighttime pumping stages in a clear, logical sequence, with the cyclical nature of the system generally well conveyed. Its main limitation is occasional imprecision, particularly the suggestion that water returns towards the river and the ambiguous claim that the high-level reservoir is closed at night. The priority is to describe every flow and component exactly as shown in the diagram.
IELTS Writing Criteria Scores
Detailed feedback by IELTS writing criterion after the annotated essay.
Task Achievement
The main daytime and nighttime stages are covered with a clear overview, though a few flow details are imprecise.
State that nighttime water is pumped from the low-level reservoir back to the high-level reservoir and that the intake, rather than the reservoir, closes.
Coherence and Cohesion
The report progresses logically from the overview through the daytime stage to the nighttime stage with clear referencing.
Reduce repeated references to stages and water flow so the sequence reads even more efficiently.
Lexical Resource
A sufficiently varied process vocabulary is used, although choices such as 'broadly distributed' and 'reverted' are not fully natural or precise.
Prefer exact process collocations such as 'divided into', 'released', and 'pumped back' throughout.
Grammatical Range and Accuracy
A wide range of sentence structures is handled accurately, with only minor ambiguity in some modifying clauses.
Place relative clauses next to the specific component they modify to eliminate ambiguity.
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IELTS Academic Writing Task 1
The diagram below shows how electricity is generated in a hydroelectric power station.
Your response
Write the task yourself, then compare your choices with the annotated response.