A process diagram in IELTS Academic Writing Task 1 shows how something is made or how something happens, step by step. There are two main kinds: a manufacturing process (for example, how glass bottles are recycled) and a natural process (for example, the life cycle of a frog or how rain forms). There are no numbers to compare, so examiners look at three things above all: an accurate overview, clear sequencing, and good control of the passive voice.
Read the diagram before you write
- Count the stages. Your overview will usually say how many there are.
- Find the start and the end. Is it a line from raw material to finished product, or a cycle that starts again?
- Notice the labels. You can use the words on the diagram, but change their form where you can (the label "heating" can become "is heated").
- Look for branches. Sometimes a stage splits into two, or something is recycled back to an earlier stage. Mention it.
A 4-paragraph structure
- Introduction: paraphrase what the diagram shows. "The diagram shows…" becomes "The diagram illustrates how… / the stages in…".
- Overview: the number of stages, where the process starts and ends, and (if true) whether it is a cycle.
- Body paragraph 1: the first half of the stages.
- Body paragraph 2: the second half of the stages.
Passive voice: the key grammar
In manufacturing processes, who does each step isn't important, so use the present simple passive: am / is / are + past participle.
| Active (avoid most of the time) | Passive (better for processes) |
|---|---|
| Workers collect the bottles. | The bottles are collected. |
| A machine crushes the glass. | The glass is crushed by a machine. |
| They then heat it to 1,500°C. | It is then heated to 1,500°C. |
Natural processes often use active verbs, because nobody is doing the action: the eggs hatch, water evaporates, the tadpole develops legs. Use the voice that matches what really happens.
Common errors: forgetting is/are ("the glass crushed"), using the wrong participle ("is putted", "is builded"), and singular/plural agreement ("the bottles is washed"). Check every passive verb before you finish.
Sequencing language
| Stage | Useful language |
|---|---|
| Start | The process begins with… · At the first stage… · First / Firstly… |
| Middle | Next… · Then… · After that… · Following this… · Subsequently… |
| Joining two steps | Once / After the bottles have been washed, they are… · …, before being crushed. · …, after which they are sorted. |
| At the same time | Meanwhile… · At the same time… |
| End | Finally… · At the last stage… · The process ends when… · The cycle then begins again. |
Don't start every sentence with a sequencer. Joining two stages in one sentence with once, before being or after which shows more grammatical range than a list of "Next… Then… Next…". For more on this, see linking words; the same principle applies in Task 1.
Sample answer
Task: The diagram shows how olive oil is produced. Summarise the information by selecting and reporting the main features.
Stages on the diagram (described in words): 1. olives harvested from trees · 2. transported to the mill · 3. leaves removed and olives washed · 4. crushed into a paste (including stones) · 5. paste slowly mixed for 30–40 minutes · 6. oil separated from water and solids in a centrifuge · 7. oil filtered · 8. stored in tanks, then bottled. The leftover solids are used as fuel or fertiliser.
The diagram illustrates the stages involved in producing olive oil, from the harvesting of the fruit to the bottling of the finished product.
Overall, there are eight main stages in the process, which begins on the farm and is completed at the mill. In addition, a by-product is created that can be reused rather than wasted.
At the first stage, the olives are harvested from the trees and transported to a mill. Once they arrive, any leaves are removed and the fruit is washed. The clean olives are then crushed, together with their stones, to form a thick paste, which is slowly mixed for between 30 and 40 minutes.
Following this, the paste is placed in a centrifuge, where the oil is separated from the water and solid material. The leftover solids can be used as fuel or fertiliser. Meanwhile, the oil is filtered before being stored in tanks. Finally, it is bottled and ready to be sold.
Written by BandIQ as a teaching example (about 170 words), based on a made-up diagram. Any band given for a sample like this is an estimate, not an official IELTS score.
Why it works
- The overview gives the number of stages, the start and end points, and the by-product, with no small details.
- Every stage is included and in the correct order. In a process, missing a stage is a Task Achievement problem.
- Varied structures: simple passives, a relative clause (which is slowly mixed), once they arrive, and before being stored.
- Labels are reworded ("harvested" → "the harvesting of the fruit"; "leftover solids" → "a by-product").
Task 1 is worth about a third of your Writing band, and Task 2 about two thirds. Plan your time with our Writing time management guide, and check a Task 2 essay with the free BandIQ Band Check.
Frequently asked questions
What tense should I use for a process diagram?
Usually the present simple, because the process happens regularly. Use the passive for manufacturing steps (is heated, are collected) and the active for natural steps (the eggs hatch, water evaporates).
Do I need an overview for a process diagram?
Yes. Say how many stages there are, where the process starts and ends, and whether it is a cycle. Without an overview it is hard to score above band 5 for Task Achievement.
Can I copy the words from the labels?
You can use them, especially technical terms, but change their form where possible. Turning nouns into verbs (heating → is heated) also shows grammar range.
Should I include every stage?
Yes. Unlike a graph, a process has no 'less important' data to leave out. Include every stage, in order, but group them into two body paragraphs.
Do process diagrams appear in General Training?
No. Process diagrams are only in Academic Writing Task 1. General Training Task 1 is a letter.