Band 8.5 IELTS Writing Task 1 Model Answer

Overall Band Score: 8.5 · Cambridge IELTS 14 · 2026-07-31

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 produced in a hydroelectric power system.

In the first stage, water is stored in a high-level reservoir behind a dam. During the day, when electricity demand is high, the dam’s gates are opened, and water flows down a steep pipe called a penstock due to gravity. As the water rushes down, it spins a turbine located at the bottom of the penstock. The turbine is connected to a generator, and as it rotates, the generator produces electricity. This electricity is then passed through a transformer where the voltage is increased before being sent out to the national grid via power lines.

In the second stage, at night when electricity demand is low, the process reverses. Electricity from the grid is used to run the generator as a pump. This pumps the water from a low-level reservoir back up through the penstock into the high-level reservoir, so it can be used again the next day.

overall, a hydroelectric power station works as a kind of battery. It uses water flowing downhill to generate power during peak hours and then recycles that water back uphill during off-peak hours.

AI examiner evaluation

Task Achievement / Task Response — Band 8.5

The response effectively covers all stages of the hydroelectric power generation process. You have clearly identified the two main phases: the generation of electricity during the day and the pumping process at night. The overview provides a concise summary of the system's function, which is a key requirement for Task 1. The information is accurate, and the comparison between peak and off-peak hours is well-integrated. You have successfully highlighted the main features without getting bogged down in unnecessary detail, meeting the requirements for a high band score.

Coherence and Cohesion — Band 8.5

The response is logically organized, with a clear introduction, two body paragraphs detailing the stages, and a summary overview. The progression of ideas is smooth, moving logically from the generation phase to the recycling phase. Cohesive devices such as 'In the first stage', 'As the water rushes down', and 'In the second stage' are used effectively to guide the reader through the process. Paragraphing is used appropriately to separate the distinct phases of the operation, making the text easy to follow.

Lexical Resource — Band 8.0

You have used a good range of vocabulary appropriate for a technical description, such as 'reservoir', 'penstock', 'turbine', 'generator', and 'national grid'. The language is precise and fits the context well. There is a natural flow to the terminology used, and you have avoided repetitive phrasing. While the vocabulary is accurate and functional, incorporating a few more sophisticated collocations or varied synonyms for 'process' or 'electricity' could elevate the response further, but the current range is sufficient for a high score.

Grammatical Range and Accuracy — Band 8.5

The grammar is highly accurate throughout the response. You have used a variety of complex sentence structures, such as 'During the day, when electricity demand is high, the dam’s gates are opened...' and 'Electricity from the grid is used to run the generator as a pump.' Punctuation is used correctly, and there are no significant errors that impede communication. The control over tense and voice is consistent, particularly in the passive constructions required to describe a mechanical process.

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