Band 8.5 IELTS Writing Task 1 Model Answer

Overall Band Score: 8.5 · Cambridge IELTS 14 · 2026-08-20

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 by which electricity is generated in a hydroelectric power station

Overall, the system operates in a cycle involving the storage of water in an upper reservoir, its release to drive turbines for power generation, and the subsequent transfer of water to a lower reservoir. At times, water is pumped back to the upper reservoir to maintain the cycle.

In detail, water is initially collected from a river and stored in a high-level reservoir behind a dam. During periods of high demand, typically daytime, intake gates open, allowing water to flow down through pipes into the power station. This flowing water spins the turbines, which drive generators to produce electricity. The generated electricity is then transmitted via power lines to the national grid. After passing through the turbines, the water flows out into a low-level reservoir.

When electricity demand is low, usually at night, the process can be reversed. Water from the low-level reservoir is pumped back up to the high-level reservoir using surplus electricity, ready to be released again when needed.

AI examiner evaluation

Task Achievement / Task Response — Band 8.5

The response is excellent and fully addresses all parts of the task. You have clearly identified the main features of the hydroelectric power generation process, including the two distinct phases: power generation during high demand and the pumping cycle during low demand. The overview provides a concise summary of the entire process, and the body paragraphs logically detail the stages of the cycle. You have successfully highlighted the key comparisons between the two states of the system, demonstrating a clear understanding of the diagram. The information is accurate, well-selected, and presented in a professional, academic tone suitable for Task 1.

Coherence and Cohesion — Band 8.5

The response is logically organized and flows smoothly from the introduction to the detailed process description. Each paragraph has a clear central theme, and the progression of ideas is easy to follow. You have used cohesive devices effectively, such as 'In detail', 'During periods of high demand', and 'When electricity demand is low', which help to guide the reader through the stages of the process. The use of referencing is precise, ensuring that the relationship between the reservoirs, turbines, and generators is clear throughout the text. Paragraphing is used appropriately to separate the overview from the specific process steps.

Lexical Resource — Band 8.0

You have demonstrated a wide and precise range of vocabulary appropriate for a technical process description. Terms such as 'hydroelectric power station', 'intake gates', 'surplus electricity', and 'national grid' are used accurately and naturally. The vocabulary is sophisticated and contributes to the clarity of the explanation. There are no noticeable errors in word choice or collocation, and the language used is consistently academic and formal. The range of vocabulary is sufficient to convey complex mechanical processes with ease and precision.

Grammatical Range and Accuracy — Band 8.5

The response exhibits a wide range of grammatical structures, including complex sentences that are handled with high accuracy. Your use of participial phrases (e.g., 'allowing water to flow down') and passive voice constructions (e.g., 'water is initially collected', 'is then transmitted') is perfectly suited to describing a technical process. The majority of your sentences are error-free, and the punctuation is used correctly throughout. There is a high level of control over complex sentence forms, and the overall grammatical accuracy is excellent, with no slips that impede communication or distract the reader.

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