What does a process-diagram question test?
In IELTS Academic Writing Task 1, you may be asked to describe a graph, table, chart or diagram. IELTS says a diagram can require you to describe stages of a process or procedure, explain how something works, or describe a sequence of events. The minimum is 150 words and the recommended time is about 20 minutes.
The four Writing criteria still apply: Task Achievement, Coherence and Cohesion, Lexical Resource, and Grammatical Range and Accuracy. That means an accurate sequence is only part of the job; your organisation and language also matter.
The 4-part structure
1. Introduction: paraphrase what the diagram shows without copying the prompt word for word.
2. Overview: summarise the process at a high level: the broad start and end, number of main stages, or whether it is linear or cyclical.
3. Body paragraph 1: describe the early stages in logical order.
4. Body paragraph 2: continue through the later stages to the final result.
IELTS preparation guidance specifically highlights the importance of identifying key features and including an overview. For process tasks, the key features are the important steps or stages rather than numerical peaks or comparisons.
How to write the overview
A weak overview repeats the introduction. A useful overview tells the reader what the process looks like as a whole.
Example overview
Overall, the process consists of six main stages, beginning with the collection of used glass and ending with newly formed bottles being packaged for distribution.
Notice that the overview does not list every stage. It gives the examiner a clear map of the process before the details begin.
Sequencing language that sounds natural
Use sequence markers when they genuinely help the reader follow the stages: initially, next, following this, once this stage is complete, subsequently, finally. Avoid starting every sentence with “then.”
You can also connect stages grammatically: “After the material is washed, it is sorted by colour,” or “Once the mixture has been heated, it is transferred to the moulding stage.”
Passive voice: useful, not compulsory
Manufacturing diagrams often focus on what happens to a material rather than who performs the action. That makes passive forms useful: “the glass is crushed,” “the pieces are heated,” “the liquid is poured.”
Do not force passive voice into every sentence. For natural processes, active structures may be clearer: “the seed germinates,” “the plant develops leaves,” or “water evaporates.” Grammar should serve accuracy and clarity.
Original IELTS-style worked example
Task
The diagram shows how used glass bottles are recycled and turned into new bottles. Summarise the information by selecting and reporting the main features.
Model response
The diagram illustrates the process used to recycle discarded glass bottles and manufacture new containers from the recovered material.
Overall, there are six main stages in this linear process, starting with the collection of used bottles and finishing with the packaging of newly manufactured bottles for distribution.
Initially, empty glass bottles are collected from designated recycling points and transported to a processing facility. At the plant, they are washed thoroughly before being separated according to colour. The sorted glass is then crushed into small pieces.
Following this, the crushed material is heated at a high temperature until it becomes molten glass. This liquid is poured into bottle-shaped moulds and allowed to cool. In the final stage, the newly formed bottles are inspected, packed and prepared for delivery.
This example is original CBI Prep practice content designed to reflect the task type; it is not an official IELTS question or model answer.
Common mistakes
Missing the overview: describing every stage without summarising the process as a whole.
Inventing information: explaining why a stage happens when the diagram does not say so.
Listing instead of grouping: producing one short sentence for every arrow rather than coherent paragraphs.
Overusing “then”: relying on one connector instead of varied grammatical sequencing.
Ignoring the end product: stopping before the final stage or failing to show how the process concludes.
A 20-minute practice routine
Use roughly 3 minutes to identify the start, finish, major stages and two logical body groups. Spend about 14 minutes writing, then reserve the final 3 minutes to check sequence, missing stages, verb forms, articles and spelling. The exact split can vary, but practising under a fixed time limit helps you build a repeatable workflow.
Continue with IELTS Writing practice, review the Writing band score criteria, or compare this task type with the Task 1 line graph guide.
Practise under test conditions
Move from the strategy to timed computer-based practice so planning, typing and reviewing become automatic.
Frequently asked questions
How long should I spend on IELTS Writing Task 1?
IELTS recommends about 20 minutes for Academic Writing Task 1. You must write at least 150 words, while Task 2 carries more weight in the overall Writing score.
Do process diagrams need an overview?
Yes. IELTS preparation guidance states that a clear overview is important for stronger Task Achievement. For a process, the overview should summarise the number or broad pattern of stages, such as where the process begins and ends or whether it forms a cycle.
Should I use passive voice for every sentence?
No. Passive voice is often useful for manufactured processes because the action matters more than the person doing it, but it should be used only where it fits naturally. Natural processes often need a mixture of active and passive structures.
Can I add reasons that are not shown in the diagram?
No. Academic Task 1 asks you to report the visual information. Keep your description based on the stages and details shown rather than inventing causes, opinions or background information.
Official references
This guide was checked against current IELTS Academic Writing format and Writing assessment guidance. Always use your test provider's current instructions on test day.