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 water flowswhen the water flows from the river into a high-level reservoir and includesends with the transmission of electricity to the national grid. In general, the process is broadly divideddistributed into day and night stages with the daytime stagedaylight stages involving electricity generation using descending waterelectricity production from a river and storage of discharged water in the low-level reservoirstorage of water in a reservoir. At night, the water flows back in the opposite direction towards an initial reservoir and the river. The daytimeday stage of the process involves channelling the river water into a high-level reservoir held back by a dambacked up by a dam. There is an intakeintake 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 reversible turbinespower station turbines. The generated electricity is then sent to thea national grid through power lines while the theexcess water flows intoruns 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 in the high-level reservoirat the upper level and later it flows down, starting the cycle again.
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
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.