Short answer: to describe a process diagram in IELTS Academic Writing Task 1, report the stages in order using the present simple passive joined by sequencers, after an introduction that paraphrases the prompt and an overview that names how many stages there are and what the process starts and ends with.
There are no figures, so there are no trends — the marks are in stage accuracy, sequencing and the passive.
Process diagrams — sometimes called process charts or flow diagrams — turn up far less often than line graphs and bar charts.
That is precisely why they cost so many candidates half a band: months of practice goes into describing trends, and then a diagram of brick manufacturing appears with not a single number on it, and every rehearsed phrase about "a sharp increase" is useless.
This guide covers the grammar the task actually needs, the two structural shapes a process can take, the phrase banks for sequencing, and a full annotated model answer.
If your Task 1 preparation has only covered data visuals, start with the Task 1 hub for how all seven visual types compare, then come back here.
What is a process diagram in IELTS Writing Task 1?
A process diagram shows how something is made, how a system works, or how a natural cycle develops. Instead of axes and values, you get boxes, arrows and labels.
Typical subjects are manufacturing (recycled paper, bricks, instant coffee, cement), natural cycles (the water cycle, the life cycle of an insect) and systems (how a water filter or a hydroelectric dam works).
The task instruction is the same as for every Academic Task 1 question: summarise the information, select and report the main features, and write at least 150 words in about 20 minutes. What changes is what counts as a "main feature".
On a line graph it is a trend; on a process it is a stage, and its position in the sequence.
Linear or cyclical: the decision you make first
Every process diagram is one of two shapes, and telling them apart before you write is worth more than any phrase bank.
| Shape | How to recognise it | What your overview says | How you end |
|---|---|---|---|
| Linear | The arrows run from one thing to a different thing and stop — raw clay in, packaged bricks out | The number of stages, the raw input, the final output | With the final stage: packaging, delivery, sale |
| Cyclical | The last arrow returns to an earlier stage — evaporation, condensation, precipitation, and back | That the process is continuous, and the point it returns to | By closing the loop: "at which point the cycle begins again" |
Getting this wrong is expensive. A candidate who describes the water cycle as though it finishes when rain hits the ground has misrepresented the diagram's single most important feature, and Task Achievement is where that is charged.
Why the present simple passive, and when to break it
Two grammar choices carry most of the Grammatical Range and Accuracy marks on a process.
Tense: present simple. A process diagram describes what happens every time, not what happened once. "The beans are roasted" is right; "the beans were roasted" describes a single past occasion the diagram never claimed.
Voice: passive, for anything manufactured. Look at the diagram: it almost never shows who does each stage. The passive exists for exactly this situation — when the action matters and the agent is unknown or irrelevant.
| Weaker (active, invented agent) | Stronger (passive) | Why |
|---|---|---|
| Workers collect the leaves. | The leaves are collected. | The diagram shows no workers. You invented them. |
| A machine crushes the clay. | The clay is crushed. | Unless the machine is labelled, naming it is added detail. |
| They heat the mixture to a high temperature. | The mixture is then heated. | "To a high temperature" is a figure the diagram did not give. |
The exception: natural cycles take the active voice. In the water cycle nobody evaporates the water — it evaporates. "Water evaporates from the ocean's surface" is correct and "water is evaporated" is wrong.
The rule underneath both cases is the same: use the passive when there is an unstated human agent, and the active when the subject genuinely does the action itself.
Sequencing language: the phrase bank
Coherence and Cohesion on a process is largely about sequencing without repeating yourself. Six uses of "then" is the most common cohesion problem in a band 6 process answer.
| Position | Phrases | Example |
|---|---|---|
| Opening stage | initially · to begin with · at the first stage · the process begins when | The process begins when raw cane is delivered to the mill. |
| Middle stages | next · subsequently · after this · following this · at the third stage | Subsequently, the pulp is passed through a series of rollers. |
| Simultaneous | meanwhile · at the same time · while this happens | Meanwhile, the waste fibre is separated for reuse. |
| Dependent stage | once X is complete · after being heated · having been dried | Once the moulds have set, the bricks are removed. |
| Final stage | finally · in the final stage · lastly | Finally, the finished product is packaged for distribution. |
| Closing a cycle | at which point the cycle begins again · thereby completing the cycle | …returns to the ocean, thereby completing the cycle. |
Two habits raise the band here. First, vary the grammar of the sequencer, not just the word: mix adverbs ("subsequently") with participle clauses ("having been dried") and time clauses ("once the moulds have set").
Second, do not signpost every single stage — a paragraph where all five sentences begin with a sequencer reads as mechanical, which is the Coherence equivalent of listing.
Vocabulary: paraphrase the labels, do not replace them
The labels on the diagram are technical terms you are expected to use. "Fermentation tank" has no synonym, and inventing one loses accuracy rather than showing range. Lexical Resource on a process is earned in the verbs and in how you refer back to stages you have already named.
- Precise process verbs: crushed, ground, sieved, filtered, refined, moulded, compressed, heated, cooled, dried, sealed, distributed — chosen accurately rather than impressively.
- Referring back: "the resulting mixture", "this liquid", "the crushed material", "the semi-finished product". This is where a process answer shows cohesion without another sequencer.
- Nominalisation for the overview: "the manufacture of instant coffee involves seven distinct stages" reads at a higher band than "there are seven stages to make instant coffee".
Model answer: a seven-stage linear process
Written as a teaching example for this article — not a real or predicted exam question. The diagram it describes shows how instant coffee is produced, in seven labelled stages: harvesting, drying, roasting, grinding, brewing, freeze-drying, packaging.
The diagram illustrates the process by which instant coffee is manufactured, from the harvesting of the beans to the packaging of the finished product.
Overall, the manufacture of instant coffee involves seven distinct stages. It is a linear process which begins with the picking of ripe coffee cherries and ends with a powdered product sealed in jars for sale.
Initially, ripe cherries are harvested from coffee plants and transported to a processing facility, where they are spread out and left to dry. Once the beans have been dried and separated from the fruit, they are roasted at the third stage, which develops their colour and flavour. The roasted beans are subsequently ground into a coarse powder.
In the second half of the process, the ground coffee is brewed with hot water to produce a concentrated liquid. This concentrate is then frozen and passed through a freeze-drying unit, where the ice is removed and only soluble coffee granules remain. Finally, the granules are weighed, sealed into jars and prepared for distribution.
172 words.
Why this would score around Band 8
| Criterion | What the answer does |
|---|---|
| Task Achievement | Paraphrased introduction, a genuine overview naming the stage count and both endpoints, all seven stages reported in the correct order, and nothing invented — no temperatures, no durations, no causes. |
| Coherence & Cohesion | Split at a real structural break (bean preparation, then liquid processing), and the break is named. Sequencers vary in grammar: an adverb, a time clause, a participle, a final adverb. Back-reference ("this concentrate", "the granules") replaces a sequencer twice. |
| Lexical Resource | Accurate process verbs (harvested, roasted, ground, brewed, sealed), the diagram's technical labels used as given, and one nominalisation in the overview. |
| Grammatical Range & Accuracy | Present simple passive throughout, with a relative clause, a present-perfect time clause and a "where" clause providing range rather than decoration. |
The five mistakes that cap a process answer
- Describing trends that do not exist. There are no numbers, so "increased sharply" cannot apply to anything. This is the single clearest sign of a candidate who prepared only for graphs.
- No overview. A process answer that opens straight into stage one is capped on Task Achievement regardless of how accurate the sequence is.
- The wrong voice. Active with an invented agent on a manufacturing process ("workers pour the mixture"), or passive on a natural cycle ("water is evaporated").
- Inventing detail. Durations, temperatures, quantities and reasons that the diagram never showed. The examiner has the diagram; added detail is visibly added.
- One sentence per stage, all starting with "then". Accurate but mechanical, which is a Coherence and Cohesion problem — the fix is grouping and grammatical variety, not more linking words.
How to practise process diagrams when they are rare
The shortage of practice material is a real problem: most question banks are dominated by graphs. Two things work.
Convert any process you can find into a Task 1 prompt. A recipe, a manufacturing explainer, an instruction manual diagram, the assembly steps in flat-pack furniture instructions — all of these are stage sequences with an unstated agent, which is exactly the grammar the task tests. Write 150 words on it in 20 minutes.
Then get the report marked rather than self-assessed. The two things that decide a process answer — whether the overview is a real overview, and whether the passive is used correctly and consistently — are both hard to judge in your own writing.
You can paste a process report into the Writing Checker for a band on each of the four criteria, and if you have a diagram image you can upload it so the marking accounts for what the diagram actually showed.
For a timed sitting with both tasks on one clock, use the Writing mock test.
And once the method is automatic, spend the remaining time on Task 2 — it carries twice the weight of Task 1 in your final Writing band.