# IELTS Process Diagrams: Sequence and Passive Voice | topin

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## Follow arrows before choosing vocabulary

Identify the starting material or event, the final output, each intermediate operation and any branch or return arrow. A row of boxes can describe a linear process; a return arrow can create a cycle. Two outgoing arrows can indicate parallel routes. Read those relationships before deciding whether the overview should say stages, branches or cycle.

Make a verb beside each stage: collect, sort, wash, crush, mould and cool, for example. These verbs are working notes, not the completed response. Check that each comes from the diagram's meaning. If a box says heat, do not add a temperature unless one is given. Understanding the process does not permit you to supplement missing technical facts.

The [Academic Writing specification](https://ielts.org/take-a-test/test-types/ielts-academic-test/ielts-academic-format-writing) includes descriptions of processes. British Council's active/passive guidance helps with grammatical choices. This guide provides original teaching examples so you can practise those choices without copying an official manufacturing diagram or answer.

Count stages consistently if you mention a count. A transport arrow is not necessarily a separate production operation, and a storage label may or may not be treated as a stage in your outline. The safest overview can describe the broad sequence without an exact count if the visual makes the count ambiguous.

## Read an original linear process and its two output streams

Original exercise: used plastic trays are collected and sorted. Suitable trays pass to a wash tank; unsuitable items leave the system for separate handling. The washed trays are crushed into flakes. The flakes are heated, pressed into moulds and cooled. The cooled trays are inspected. Accepted trays are packed, while rejected trays return to the crushing stage.

There are two distinctions to capture: early removal of unsuitable material and later reprocessing of rejected products. Calling the entire process a simple straight line would miss the return route. Calling it a natural cycle would also be inaccurate: it is a manufacturing system with a reprocessing loop, not a repeating ecological event.

A useful overview is: “Used trays are transformed into new products through sorting, cleaning and remoulding, with unsuitable material removed early and rejected finished trays returned for reprocessing.” The sentence summarises the structure and output without listing every box. It prepares the reader for the branch descriptions in the body.

Use the [overview examples](/articles/ielts-task-1-overview-examples) to check that this summary does more than announce a diagram. Then group the body into input preparation and production/inspection. This grouping is our suggested plan, not a requirement for exactly two body paragraphs or a particular number of sequence words.

## Use passive for actions received, active for events performed

__Original grammar repairs__
| Draft                              | Repair                          | Reason                                           |
| ---------------------------------- | ------------------------------- | ------------------------------------------------ |
| The trays washed.                  | The trays are washed.           | Passive needs an auxiliary here                  |
| The flakes is heated.              | The flakes are heated.          | Plural subject agreement                         |
| The material is crush.             | The material is crushed.        | Past participle required                         |
| The water is evaporated naturally. | The water evaporates naturally. | Active event description fits the stated meaning |

“The trays are washed” focuses on material receiving an action. It uses a form of be plus the past participle. “The water evaporates” uses active voice because evaporation is an event performed by the subject in the description. The choice follows meaning, not a rule that process diagrams require passive sentences everywhere.

For a standard process described without historical dates, present simple is a useful default: trays are sorted and flakes are heated. If the prompt describes a past system, change tense accordingly. Do not switch tense simply to add grammatical variety. Time reference should stay consistent with the supplied information.

Avoid inventing an operator. “Workers wash the trays” adds people the exercise does not specify. “The trays are washed” makes no unnecessary actor claim. Conversely, if the diagram explicitly shows a named machine performing an action, an active sentence can be clear: the press shapes the softened material.

British Council's [voice guidance](https://takeielts.britishcouncil.org/blog/using-active-vs-passive-voice-in-ielts-writing-and-speaking) explains the structural distinction. Use the error table above to practise it on original sentences. A passive structure only helps if the verb form, agreement and process relationship remain accurate; it is not a bonus attached to the word are.

## Study an original response with branches and reprocessing

Original model response: The diagram outlines a system for turning used plastic trays into new ones. Overall, the material is prepared and remoulded before inspection, with unsuitable items removed near the beginning and rejected finished trays returned for another production attempt.

First, used trays are collected and sorted. Those considered suitable enter a wash tank, whereas unsuitable items are removed from the system for separate handling. After washing, the trays are crushed into flakes. These flakes are then heated and pressed into moulds to form new trays, which are subsequently cooled.

The cooled products pass through an inspection stage. Trays that meet the required standard are packed, completing the main production route. In contrast, rejected trays are sent back to the crushing stage, allowing their material to pass through heating, moulding and cooling again. This return route differs from the early removal of unsuitable items, which do not continue through the process shown.

This original teaching response is not an official sample or an assigned band. Its final sentence clarifies a relationship that a box-by-box list could obscure. The answer does not supply a wash duration, heating temperature, inspection threshold or delivery destination because the exercise provides none. Precision includes omitting attractive but unsupported details.

## Check sequence, grammar and references separately

A sequence error can make correct grammar describe the wrong system. For example, “After the trays have been packed, they are inspected” reverses the final operations in this exercise. Read arrows again before polishing language. If your sentence says after, before or until, identify the two events it links and verify their order.

An agreement error is different: “The flakes is heated” should be “The flakes are heated”. A missing passive auxiliary creates another problem: “The trays washed” does not describe the standard operation correctly here. A wrong participle such as “are crush” needs “are crushed”. Keep these error types separate in your log so the next exercise targets the real weakness.

References also need attention. “They are heated” can be unclear after a sentence discussing suitable trays and unsuitable items. Name the material at the transition: “The resulting flakes are heated.” The [cohesion and referencing guide](/articles/ielts-writing-cohesion-referencing) explains how a clear noun phrase can be more useful than a vague pronoun.

Use sequence language selectively. First, after washing and finally can help, but beginning every sentence with then makes the report repetitive. Relative clauses and time clauses can combine closely related stages when you control the grammar. Clarity of order is the goal; variation should serve that goal instead of adding difficult structures for appearance.

## Practise one grammar choice inside a complete process report

Start with six short process sentences and choose active or passive based on the action. Explain each choice. Then combine two adjacent stages with after or before and check the order. This short exercise isolates meaning and grammar before the time pressure of a complete response. It is a suggested practice routine, not an IELTS stage-count rule.

Next describe a fresh process with a branch. Draw a simple note of where the branch leaves and where it goes. Include that relationship in prose, and check that your overview still summarises the system accurately. A branch is often the feature that separates a meaningful report from an unconnected sequence of operations.

Write a full response in the recommended Task 1 allocation, with at least 150 words, then return to the broader [Academic Task 1 guide](/ielts/writing/task-1) for complete-task review. Compare the original timed version with your revised version. Keep the first one so recurring errors are not hidden by later editing.

[topin's free IELTS Academic mock](/ielts/practice-test), marked on the official scale, can test whether this method works alongside the essay. Inspect the balance between planning, drafting and checking. If you spend too long inventing vocabulary for machinery, simplify to accurate verbs supported by the diagram. The complete report should make the shown system easier to follow.

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## FAQs

Must every process sentence be passive?

No. Use passive for material receiving an action when the actor is unimportant. Natural events and named actors can use active verbs.

Which tense should I use?

Follow the prompt’s time reference. Present simple is useful for a standard process without historical dates.

Can I add a temperature I know from science?

No. Use the supplied diagram’s information; do not add outside technical details.

How do I describe a return arrow?

State where the material returns and what is repeated. Distinguish a reprocessing loop from material leaving the system.

Do I have to count every stage in the overview?

No fixed counting requirement is imposed here. Describe the main structure accurately, and use a count only when it is clear and consistent.

## Sources (checked 5 October 2026)

* [IELTS: Academic Writing specification — checked 5 October 2026](https://ielts.org/take-a-test/test-types/ielts-academic-test/ielts-academic-format-writing)
* [British Council: active and passive voice — checked 5 October 2026](https://takeielts.britishcouncil.org/blog/using-active-vs-passive-voice-in-ielts-writing-and-speaking)
* [IELTS: public Writing band descriptors — checked 5 October 2026](https://ielts.org/cdn/Guides/ielts-writing-band-descriptors.pdf)
* [British Council: selecting and writing Task 1 overviews — checked 5 October 2026](https://takeielts.britishcouncil.org/sites/default/files/2026-06/academic%5Fwriting%5Ftask%5F1%5Fwriting%5Fthe%5Foverview.pdf)

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