These two books are worth opening when something specific is waiting behind them, and are close to worthless when nothing is. The words are rare enough that a month can pass without one of them appearing anywhere in your life, and a word that goes a month unused after a single week of study is gone.
That is not an argument against the band. It is an argument about sequencing: get the reason first, then the book. An exam with a date, a degree reading list, a field you have to follow in English, any of those turns these six hundred words into a working set. Nothing at all turns them into one on their own.
Sixteen from this band, with a sentence for each
This band is where English turns formal. These words appear in reports, contracts and news writing far more than in speech.
- accumulate, to build up gradually. Dust accumulated behind the radiator all winter.
- adequate, enough, but only just. The lighting was adequate for reading and no better.
- ambiguous, open to more than one reading. The clause was ambiguous and both sides read it their own way.
- comply, to act in accordance with a rule. The workshop complied with the new noise limit by March.
- deteriorate, to get worse over time. The path deteriorated badly after two wet winters.
- diminish, to become less. Interest diminished once the free trial ended.
- implement, to put a plan into effect. They implemented the new rota in the second week of term.
- inevitable, certain to happen. A second delay was inevitable once the parts were held at the border.
- integrate, to combine into a whole. The booking system was integrated with the till in one afternoon.
- justify, to show something is reasonable. She could not justify the cost to the trustees.
- notion, an idea, often a loose one. The notion that the shop would close was never official.
- presume, to suppose something is true without proof. He presumed the meeting was cancelled and nobody had told him.
- reluctant, unwilling and doing it anyway. The landlord was reluctant to replace the boiler.
- substantial, large in amount or importance. A substantial part of the roof needed replacing.
- sustain, to keep something going, or to suffer damage. The pace was hard to sustain past October.
- undergo, to experience something done to you. The building underwent repairs for most of the summer.
What changes at this band
Below here, a word list is a shortcut and reading is a slower route to the same place. Here, reading stops supplying the words at all for most learners, because the encounters are too far apart to build anything, and the list becomes the only route. That is the argument for the band and it is a real one.
The catch arrives immediately after. The same rarity that stops reading from teaching you these words also stops your week from rehearsing them, so the list gets them in and nothing keeps them. Every learner who has worked through the last two books and found the words gone by the spring met this, and almost all of them concluded they had studied badly.
Where it stops: finishing book four and continuing out of momentum
This is the stall, and it is caused by the set being numbered. Four is done, so five is next, and the decision is made by the spine rather than by anything in your life. The first weeks feel like the earlier books because studying feels the same regardless of what is being studied, and the loss shows up months later as a vague sense that none of it stuck.
Nothing corrects it because nothing tests it. Below this band, forgetting a word is noticed the next time you need it. Here you do not need it, so the forgetting is silent, and a learner can complete both books with high unit scores and finish with almost nothing added.
Etymology as the only hook this band offers
Wiktionary is free, needs no account, and its etymology sections are unusually thorough, which matters more here than anywhere else. Words in this band are overwhelmingly Latin and Greek, they are long, and they are built from parts, so reluctant stops being nine arbitrary letters once you know it was a struggling against. It replaced the printed etymological dictionary, which few learners have ever opened and which cost more than the coursebook.
Two limits, and they matter. It is a wiki, so coverage and quality are uneven, and an etymology is a story rather than a definition: knowing where a word came from helps you hold on to it and tells you nothing about which nouns it stands beside or how formal it is. Use it as a memory hook and check the meaning somewhere edited.
What it looks like when it goes wrong
The recognisable failure is a word produced correctly in an essay and unrecognised in a lecture, because it was learned as a shape on a page and never heard. This band is where that split gets widest: these are words a learner has typically read and never once heard said, and several of them are stressed somewhere other than where the spelling suggests.
The second failure is reaching for one of these in speech, where it lands as a word chosen to impress rather than to mean something. That is a register error rather than a vocabulary error, and it is the reason a band aimed at reading and exams should mostly stay there.
The band underneath, which nearly everybody should finish first, is mid level words for opinions, work and abstract ideas, and how the six are paced against each other is the core word list, worked through one book at a time.
If the reason waiting behind these books is an exam or a degree, then the more efficient list is not this one at all. There is a set of a few hundred families that carries academic argument across every discipline, and it was counted rather than chosen: the vocabulary that carries essays, papers and lectures.