Lexical Resource: Why a Bigger Vocabulary Is Not the Answer

The most common vocabulary strategy in IELTS preparation is a list: fifty impressive words, memorised and deployed. The band descriptors describe where that strategy leads. At band 6, they note that a writer who takes risks will show a wider range of vocabulary, but with more inaccuracy and more words used inappropriately. Range without control does not move the band. Lexical resource measures how well you use the words you know, and precision beats rarity at every level.

This guide is part of our series on the four Writing criteria; the hub is How IELTS Writing Is Marked, and the previous part covered coherence and cohesion. Lexical resource applies to both Writing tasks, and a criterion of the same name scores your Speaking test, so control here pays twice.

What lexical resource measures

The official key assessment criteria list what examiners weigh: the range of general vocabulary you use, including synonyms to avoid repetition; whether your vocabulary is adequate and appropriate for the topic; the precision of your word choice; your control of collocations and idiomatic expressions; and the density and communicative effect of errors in spelling and word formation.

Two details in that list deserve attention. Spelling has no separate criterion anywhere in the test; it lives here, and the descriptors track it at every band. And errors are weighed by their communicative effect: an error that obscures your meaning costs more than one the reader glides past.

The ladder from band 5 to band 8

At band 5, the resource is limited but minimally adequate. Simple vocabulary may be used accurately, but the range does not allow much variation, word choice often slips, and spelling errors may cause the reader real difficulty.

At band 6, the resource is generally adequate for the task. Meaning comes through clearly despite a fairly restricted range or a lack of precision in word choice. Errors in spelling and word formation occur, but they do not impede communication.

At band 7, there is enough resource for some flexibility and precision. The writer shows some ability to use less common and idiomatic items, an awareness of style and collocation is evident even though inappropriate choices still occur, and only a few spelling or word formation errors appear.

At band 8, a wide resource is used fluently and flexibly to convey precise meanings, with skilful use of uncommon and idiomatic items where they fit, despite occasional inaccuracies in word choice and collocation.

What changes from band 6 to band 7

Band 6 is clear but plain: meaning survives a restricted range. Band 7 adds two things, and neither is a rare word for its own sake. The first is precision, choosing the word that says exactly what you mean rather than roughly what you mean. The second is collocation, knowing which words belong together, so you write heavy rain and make a decision rather than strong rain and do a decision. Less common vocabulary earns credit at band 7 only when it is used accurately and naturally. A rare word used wrongly counts against you where a plain word used correctly would not.

Building resource that scores

Learn words in partnerships, not in isolation. A vocabulary notebook organised by collocation, verb with noun and adjective with noun, builds the control band 7 describes, where a list of single words builds the wider but less accurate range band 6 warns about.

Learn topic families. Task 2 prompts return to the same territory: education, work, technology, the environment, health. Precise vocabulary in those areas is worth more than exotic vocabulary you never get to use.

Keep a spelling log. Spelling errors count at every band, and they tend to repeat: find the words you personally get wrong and drill them until they are automatic.

Avoid bolted on chunks. The descriptors flag memorised phrases and formulaic language low on the scale. A phrase that could open any essay tells the examiner nothing about your resource.

Next in the series: grammatical range and accuracy, where the same principle, control over ambition, decides the band.

The public Writing band descriptors and key assessment criteria are published on ielts.org. Descriptors updated May 2023; last checked August 2026.