Band 8.5 IELTS Writing Task 1 Model Answer

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

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 process of electricity generation and water management within a hydroelectric power station during daytime and nighttime operations.

Overall, the system functions as a two-stage cycle. During the day, water flows downhill to generate electricity for the national grid, while at night, the process is reversed to pump water back up to the main reservoir for future use.

In the daytime phase, the intake from the high-level reservoir is kept open. Water fed by a river behind the dam flows down through an underground pipe towards the power station. This downward rush of water drives reversible turbines, which operate a generator inside the power station. The electricity produced is then transmitted via power lines directly to the National Grid. After passing through the turbines, the water is discharged and stored in a low-level reservoir.

Conversely, during the night, the entire operation changes direction. The main intake at the top is closed, and the reversible turbines switch to pumping mode. Utilizing electricity, these turbines pump the stored water from the low-level reservoir back up through the same pipe and into the high-level reservoir, readying the system for the next day's power generation.

AI examiner evaluation

Task Achievement / Task Response — Band 8.5

The response is excellent. You have clearly identified the two-stage cycle of the hydroelectric power station, effectively contrasting the daytime generation phase with the nighttime pumping phase. The overview is concise and captures the main features of the process, and the body paragraphs provide a logical, step-by-step description of the mechanism. You have successfully integrated the information from the diagram without omitting any key components, such as the reservoirs, turbines, and the National Grid. The comparison between the two phases is well-developed, making the process easy to follow for the reader.

Coherence and Cohesion — Band 8.5

The essay is logically organized with a clear progression of ideas. Each paragraph has a distinct focus, moving from an introduction and overview to the specific details of the daytime and nighttime operations. You have used cohesive devices effectively, such as 'Conversely', 'During the day', and 'After passing through', which help to guide the reader through the process smoothly. The paragraphing is appropriate, and the transition between the two modes of operation is seamless. There is no evidence of mechanical or repetitive use of linking words.

Lexical Resource — Band 8.0

You have demonstrated a wide and precise range of vocabulary appropriate for a technical process description. Terms such as 'downward rush', 'reversible turbines', 'discharged', and 'national grid' are used accurately and in the correct context. The language is natural and sophisticated, showing a high level of control over word choice and collocation. There are no spelling errors, and the vocabulary used contributes significantly to the clarity and professional tone of the report.

Grammatical Range and Accuracy — Band 8.5

The response displays a wide range of grammatical structures with high accuracy. You have successfully used complex sentences, such as 'Water fed by a river behind the dam flows down through an underground pipe towards the power station', and maintained control over tense and voice throughout the description. Punctuation is used correctly to manage sentence flow. The writing is virtually error-free, with only rare, minor slips, which is consistent with the highest band descriptors for grammatical accuracy.

See this exact question answered at other band scores — the same prompt compared across bands.

Browse more IELTS Writing model answers or get your own writing scored by the same AI examiner.