Band 8.5 IELTS Writing Task 1 Model Answer

Overall Band Score: 8.5 · Cambridge IELTS 14 · 2026-08-23

IELTS Writing Task 1 question

The diagram below shows how electricity is generated in a hydroelectric power station.

Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

Student answer (Band 8.5)

The diagram illustrates the operation of a hydroelectric power station, showing how water is circulated between a high-level and a low-level reservoir to generate electricity during the day and pump water back uphill at night.

Overall, the system operates in two distinct phases. During the daytime, water flows downhill from the high-level reservoir through reversible turbines, generating electricity that is transmitted to the national grid. At night, the process is reversed, with the turbines functioning as pumps to return water to the upper reservoir.

During the day, the intake at the high-level reservoir is opened, allowing water to flow through a large pipe towards the power station. As the water travels downhill, it passes through reversible turbines, which drive a generator located above them. The generator produces electricity, which is then transmitted via power lines to the national grid. After passing through the turbines, the water is discharged into the low-level reservoir.

At night, the intake at the high-level reservoir is closed and the direction of water flow is reversed. Electricity is used to operate the reversible turbines as pumps, drawing water from the low-level reservoir and forcing it back through the pipe towards the high-level reservoir. The water is therefore stored at a higher elevation and is ready to be released again during the following daytime period. This continuous cycle enables the power station to generate electricity during the day while replenishing its water supply at night.

AI examiner evaluation

Task Achievement / Task Response — Band 8.0

The response is excellent. You have clearly identified the two main phases of the hydroelectric process: the daytime generation phase and the nighttime replenishment phase. The overview effectively captures the cyclical nature of the system, and the body paragraphs provide a logical, step-by-step description of the mechanical process. You have successfully highlighted the key features, such as the reversible turbines and the movement of water between reservoirs, without including irrelevant information. The report is accurate and covers all parts of the task well, meeting the requirements for a high band score.

Coherence and Cohesion — Band 8.5

The response is logically organized with a clear progression of ideas. You have used paragraphing effectively to separate the two distinct phases of the process. Cohesive devices such as 'During the daytime', 'At night', 'As the water travels', and 'therefore' are used naturally to link sentences and ideas. The flow is smooth, and the referencing (e.g., 'the process is reversed', 'this continuous cycle') is precise, ensuring that the reader can easily follow the sequence of events described in the diagram.

Lexical Resource — Band 8.0

You demonstrate a wide and precise range of vocabulary appropriate for a technical description. Terms such as 'reversible turbines', 'replenishing', 'discharged', 'elevation', and 'transmitted' are used accurately and in the correct context. The language is sophisticated and natural, showing a high level of control. There are no noticeable errors in word choice or collocation, and the vocabulary used is well-suited to the academic nature of the task.

Grammatical Range and Accuracy — Band 8.5

The writing displays a wide range of complex structures, including participial phrases ('allowing water to flow', 'drawing water from') and relative clauses. The sentences are error-free, and the punctuation is used correctly to enhance clarity. You have maintained a consistent and appropriate tone throughout. The grammatical control is excellent, with no slips or inaccuracies, reflecting a high level of proficiency in English grammar.

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