Methodology
How Kilo Lingo works
Fair question to ask of any language course: prove this is grounded in something sensible. This page is the answer - the method behind the courses, the evidence for it, and the parts of it you can try right here.
The short version: teach words in the order the language actually uses them, only ever ask learners to read or practise language built from words they have been taught, and enforce both rules with software rather than good intentions.
Where the method comes from
I learned Spanish, French, Mandarin and Russian as an adult, and I spent time teaching English in Spain and France. Two classroom memories shaped everything on this site.
I once watched a child learn the word "giraffe" in a lesson about animals - before that child could express hunger, or describe what they wanted.
Giraffe is a wonderful word and a hopeless priority. Teaching it early spends the learner's scarcest resources, memory and attention, on a word they may never need, while the hundred words that carry half of every conversation go untaught. Most courses and apps do a politer version of the same thing: vocabulary organised by theme, not by usefulness.
The second memory: hearing "immersion" invoked to justify talking at learners in language they had no way to parse. Being surrounded by noise is not immersion. What works is what the research calls comprehensible input: material pitched just above what you already know, so you can follow the meaning and let the new language attach itself to it. Chasing that idea properly is what led to the graded readers and the vocabulary ceilings below.
Frequency first: chapters of 100, blocks of 10
Each course is a sequence of chapters, and each chapter is the next 100 words of the language by real-world frequency, taught in blocks of ten. Chapter one is the hundred most common words; chapter two is words 101 to 200; and so on into the thousands. You always know why you are learning a word: it is, quite literally, the next most useful one. Giraffe is in no hurry. It can wait its turn.
- of spoken language covered by the top 1,000 word-families
- 84%
- words per chapter, in strict frequency order
- 100
- words per learning block
- 10
- lemmas in the deepest course, every one with its own page
- 5000
of spoken language covered by the top 1,000 word-families
words per chapter, in strict frequency order
words per learning block
lemmas in the deepest course, every one with its own page
Coverage figure from Nation (2006): the most frequent 1,000 word-families cover 81-84% of spoken English (BNC). Comparable figures hold across major languages by Zipf's law.
How we build the frequency lists
A frequency list is only as honest as the text it is counted from, so ours are blended from text of different registers rather than trusted to any single corpus:
Film and TV subtitles
The closest large corpus there is to everyday speech. Subtitle-derived counts anchor the conversational core of every list.
Published books
Public-domain literature keeps the written register represented, so the lists are not skewed towards the vocabulary of screenwriting.
Sentence corpora
Large collections of translated everyday sentences, which sit usefully between the spoken and written registers.
The blends are weighted, cleaned of proper nouns (unfiltered, the name "Tom" ranks in the top twenty of one popular corpus), and then lemmatised by hand: every inflected form is mapped to its dictionary headword, so "top 1,000 words" means the 1,000 most frequent lemmas - not a list padded with "speak", "speaks", "spoke" and "spoken" counted as four separate achievements. We reviewed those mappings form by form rather than trusting automatic lemmatisers, which both miss merges they should make and merge words they should not. Where a language needs special handling it gets it: Mandarin has no inflection to collapse, and the Latin corpus deliberately excludes Neo-Latin science, because a learner heading for Caesar should not have their core vocabulary shaped by Newton's optics.
The anatomy of a chapter
A chapter is not a hundred flashcards in a row. Between the word blocks sit different kinds of lesson, each with its own job - and each with its own icon, the same one everywhere on the site, so you can read the shape of a chapter at a glance.
Chapter opener
A short welcome that frames what the next hundred words will unlock.
Word lessons
The next ten words by frequency, with audio, illustrations and typed recall.
Affix lessons
Esperanto's word-building machinery: pieces that snap onto hundreds of roots.
Measure words
Mandarin's counting machinery, drilled as tappable chips.
Grammar lessons
A rule explained at your level, with a bespoke drill built from that lesson's own content.
Sound Lab
The mouth, drawn and animated. Produce the sounds, not just hear them.
Review games
Crosswords, bubble shooters and the rest of the arcade, drawing only on words you have been taught.
Mistake clinics
Two things learners keep mixing up, told apart.
Themed revision
Words you met in frequency order, regrouped into the clusters you will use them in.
Phrase sessions
Whole sentences assembled from words you already hold separately.
Songs
Real songs with lyrics, unlocked once you have the vocabulary to follow them.
Community lessons
Optional lessons that plug you into the real community: Reddit, Discord, YouTube and beyond.
Graded readers
The chapter's milestone: an original story using only vocabulary you have already met.
Chapter quiz
The summit. Pass it and the chapter's badge is yours.
Practice that varies, and never cheats
The drills between the learning blocks pull the same word out of memory through different doors - typed recall, crosswords, bubble shooters, morphology drills - with spaced repetition underneath deciding what comes back and when. Retrieval practice works best when it is not the same act every time.
The rule that makes it fair: practice only ever draws on words the course has already taught. No drill, game or quiz reaches past the point you have reached. Getting something wrong should mean you need more practice, never that the site asked you something it had not taught.
Rather than take our word for it, the box alongside is the real drill engine with real course words. No sign-up.
Try it now - no sign-up
Quick taster
3-word session
A quick mix of exercises - recognise, recall, type and build each word. Miss one and it comes back round until it sticks.
Comprehensible input, enforced by software
Every chapter ends with a graded reader: an original story written using only the vocabulary from the chapters you have already completed, followed by a comprehension quiz. That is comprehensible input made concrete - real connected prose, at length, with nothing in it you have not been taught. Grammar examples and worksheets respect the same ceiling.
"Only" is not an aspiration here; it is a build rule. Automated checks run over every story before anything ships, and one word over the chapter's vocabulary ceiling fails the build:
$ npm run check
[vocab-tier] checking 100+ graded stories against their chapter ceilings...
FAIL story uses a word beyond the learner's current chapter
The story is rewritten. The learner never sees the slip.
Human authors drift; scripts do not. Every course on the site is held to this ceiling on every commit.
As your vocabulary grows, the course opens up
A frequency-ordered course earns compound interest: every hundred words you bank makes more real material readable. So as you progress, the course introduces themed revision sessions - food, travel, work, weather - that regroup words you met in frequency order into the clusters you will actually use them in, each with its own short read. Alongside them come songs with lyrics: real songs, unlocked only once you have the vocabulary to follow them, because a lyric you can actually parse is the most pleasant spaced repetition there is. Phrase sessions do the same for conversational set pieces, built entirely from words you already hold.
Every word is a door
Behind each course sits a full dictionary of lemmas, and every target-language word shown anywhere on the site - in a lesson, a story, a grammar example, a song lyric - can be clicked for an instant definition and a link to that word's own page: example usage, illustrations to hang a mnemonic on, etymology, recorded audio, and a list of everywhere the word appears across the site.
Here is that machinery, live. Tap any word:
.
"The dog drinks water", in Esperanto.
The definition appears here.
The course points outwards
No website is a language community, and a course that pretends otherwise is keeping you captive. So the curricula include optional community lessons whose entire job is to plug you into the wider world of the language you are learning: the subreddits worth joining, the Discord servers where learners and native speakers actually talk, the YouTube channels producing input at your level, and email newsletters worth the inbox space. The measure of the course is how confidently you can leave it.
For teachers
Every drill, grammar lesson, word page and story has downloadable PDF worksheets designed to be printed and used in a classroom, and each language has a teacher's hub collecting them chapter by chapter:
If you teach and something here almost works for your classroom but not quite, tell us at hello@kilolingo.com. The worksheets exist for you, and your complaints are the roadmap.
What it costs
All of the instruction is free: every chapter, grammar lesson, story, word page and its audio, with no account needed. The Kilo Lingo Plus subscription covers the practice layer, and paying for the drills is what keeps the teaching free. More on who is behind the site on the about page.