A flow-chart puts a process in the order it happens. A passage puts it in the order the writer found interesting. Those are two different orders, and IELTS is under no obligation to make them match. A passage can explain what the storage tank is for in paragraph one and only get round to how water reaches it in paragraph three — so if you answer the boxes top-to-bottom while reading the passage top-to-bottom, you are walking two sequences in lockstep that were never in step. That observation is coaching, not an official rule: official pages verify the names of these question types and the word-limit penalty, and stay silent on strategy. We will keep the two clearly labelled throughout.
Where these tasks sit in the official list
The ielts.org Reading format pages list eleven question types, and the same list appears for both Academic and General Training. Flow-charts appear inside a grouped completion type, and diagrams get a type of their own. Quoted exactly as listed:
"Summary/note/table/flow-chart completion"
"Diagram label completion"
So officially, a flow-chart is a sibling of summary, note and table completion — one family of gap-fill tasks — while labelling a diagram (a picture of a machine, a building, a natural structure) is listed separately. What every member of the family shares is the rule that decides more marks than anything else on the page:
"A word limit is given, for example, 'NO MORE THAN TWO WORDS AND/OR A NUMBER'. You will lose the mark for writing more than the word limit." — ielts.org, Academic Reading format page
And the stakes per box:
"Each correct answer receives 1 mark. Your final score is given as a band score from 1–9 in whole or half bands." — ielts.org, Academic Reading format page
One box, one mark — a wrong box costs exactly as much as a blank one, and an over-long right answer costs the same as a wrong one.
The failure
Call it lockstep reading: assuming box 1's answer comes before box 2's answer in the passage. For sentence completion the answers do typically track the text (a coaching observation, not an official guarantee). But a flow-chart is sequenced by the process, and writers routinely describe a process out of order — purpose first, mechanism later, the humble first stage saved for last. The candidate who scans forward from their last answer sails past the paragraph they need, finds a plausible-looking noun further down, and writes it in.
One worked example
Everything below is ours — an original practice passage and chart, not official material. Instruction: Complete the flow-chart. Choose NO MORE THAN TWO WORDS from the passage for each answer.
The passage (note the paragraph order):
A. At the heart of a domestic rainwater harvesting system is a 5,000-litre underground concrete storage tank. Keeping this tank clean is the designer's main concern: a fine filter at the tank inlet polishes the water, but the real protection happens earlier.
B. Before any water reaches storage, the opening minutes of rainfall — which wash dust and bird droppings off the roof — are channelled into a small sealed chamber. Once the chamber fills, a float closes it and cleaner water flows onward. This diversion, engineers estimate, removes most of the contamination a roof collects between storms.
C. The journey begins more simply. Rain runs off the roof into gutters, where a stainless-steel mesh fitted across each channel traps leaves and moss before they can travel any further.
The flow-chart (three boxes, top to bottom):
- Rainwater leaves the roof and passes through a ______ that traps leaves.
- The dirty first flow is ______ into a sealed chamber.
- Clean water is kept in an underground ______.
Box 1 — the out-of-order trap
The chart's first step is the passage's last paragraph. A lockstep reader hunts for box 1's answer at the top of the text, meets "a fine filter at the tank inlet" in paragraph A, and writes filter — a thing that traps debris, sitting right where the first answer "should" be. But that filter belongs to the tank stage, not the roof stage. The correct answer is mesh (paragraph C: "a stainless-steel mesh... traps leaves and moss"). The chart's language is the compass: "traps leaves" points at C, wherever C happens to sit.
Box 2 — right meaning, wrong word class
Paragraph B offers two candidates that both mean the right thing: "are channelled into a small sealed chamber" and "This diversion... removes most of the contamination." The box reads "is ______ into a sealed chamber" — it needs a past participle. Write diversion and you have understood the process perfectly and produced "is diversion into a sealed chamber", which is not English. Read the gap's grammar before you read the passage — the box is a sentence, and only one word class completes it. The answer is channelled.
Box 3 — the over-limit answer
The passage says "underground concrete storage tank". The instruction says NO MORE THAN TWO WORDS. Copy the full noun phrase — concrete storage tank — and you have three words. The official line quoted above is blunt: "You will lose the mark for writing more than the word limit." No partial credit, no benefit of the doubt for extra accuracy. Storage tank (or simply tank) fits the gap and the limit. When the passage hands you a long noun phrase, the limit is telling you to prune it.
What is official here — and what is not
- Official: the type names "Summary/note/table/flow-chart completion" and "Diagram label completion"; the same eleven-type list for Academic and GT Reading; the word-limit example and its penalty; 1 mark per correct answer; 40 questions in "60 minutes (including transfer time)" with, in ielts.org's words, "no extra transfer time" unlike Listening.
- Not official: everything mechanical in this page. The claim that chart order can diverge from paragraph order, the lockstep-reading failure, the read-the-gap's-grammar move, the prune-the-noun-phrase advice — all coaching, built on how these tasks behave in practice. The official pages we rely on verify the type names and rules above and describe nothing about how to work through a flow-chart or diagram.
- Also unverified: an official Reading-specific statement that misspelled answers are marked wrong. The official spelling-penalty wording we hold is from the Listening section, so we do not quote it here as a Reading rule. Copy words exactly from the passage and the question is moot.
What actually costs you
- Answering boxes in reading order instead of process order — the single mismatch this page exists to prevent.
- Three words where two were allowed. The mark is lost outright, however right the content.
- The right idea in the wrong word class — a noun jammed into a verb-shaped gap.
- Inventing a word. Completion answers come from the passage — if your word is not in the text, it is not the answer.
- Burning minutes on one stubborn box. Every box is 1 mark; the next one may be easier.
Try one
[Try a Reading task →] — one full task, marked, no card required.