Why word frequency decides what you learn first, not a topic list

30-second version: sayit scores every word's difficulty from how often it actually shows up in real English (a frequency measure called zipf), not from a hand-picked "beginner vocabulary" list. Words rank into three bands — shown to you as Common, Less common and Rare — and the rarer the word, the less it should compete for your practice time before the common ones are solid.

Most vocabulary lists are somebody's opinion of what's "basic" versus "advanced." sayit uses a measurement instead: how frequently a word actually appears across a large sample of real English (the wordfreq frequency data, scored on a logarithmic scale called zipf — a word at zipf 6 is roughly a hundred times more common than one at zipf 4). That number, not a curriculum, is what sorts every word you encounter into a difficulty band.

The three bands

Internally the engine calls them beginner, pro and legend, mapped from the zipf score:

You'll see these as plain labels — Common, Less common, Rare — on a word card, not the internal names. That's deliberate: the internal band names happen to reuse the same words as sayit's paid-plan tiers, and printing "PRO" on a word you're trying to learn read like a paywall badge stuck onto vocabulary. The bands are purely about how common a word is; they have nothing to do with your plan.

Why frequency, not a fixed list

A hand-built "beginner words" list has to guess at what beginners need, and guesses go stale or miss regional differences. Frequency is measured, not guessed, and it self-corrects for a real problem: inflected forms. "Jumps" looks rarer than "jump" by raw frequency, because the base form absorbs most of the usage — so the engine checks a word's likely base form (jumps → jump, running → run, tried → try) and takes whichever frequency is higher. That keeps a common word's inflected forms from getting mislabeled as advanced just because of an -s or an -ing.

What this changes about how you should study

The practical consequence: don't spend equal time on every word you don't recognize. A Common word you're shaky on is worth fixing before a Rare word you've never needed. If your goal is being understood in daily conversation, Common-band words carry that weight almost entirely — Rare-band words matter far more for reading comprehension, exams, and precise writing than for everyday speech.

This is also why the Academic Word List, GRE and SAT vocabulary lists skew so heavily toward the Rare band — those exams specifically test words you won't absorb from casual exposure, which is exactly why they need deliberate practice instead of incidental pickup.

Where you'll see the band in practice

• On any word card — tap a word while reading in Read & listen or Books and the band shows alongside the definition and IPA.
• On a passage — content across the app is tagged with a difficulty level using the same three-band system, so a passage's overall level roughly tracks the density of Common versus Rare words inside it.
• Feeding your personal word list — when the engine pulls new vocabulary out of a passage you're reading (see building a word list from a book), it ranks the rarest words first, on the theory that those are the ones you're least likely to already half-know.

What frequency doesn't tell you

A word's frequency says nothing about whether you know it — plenty of learners have a strong Rare-band vocabulary from reading and a shaky Common-band one from never needing certain everyday words out loud in English. Frequency ranks the word; your own flashcards history and progress tracking are what tell you where you actually stand.

Try it: open a passage in Read & listen and tap through a few words — notice which land Common versus Rare, and whether that matches your instinct.