An app with one user

Labas

hello · LAH‑bahs

Lithuanian isn't on Duolingo. So I built my own Duolingo — the app, the teaching method, the learning engine, content, and a desktop handbook.

10 steps 12 exercise types 20 chapters planned

How it was built, step by step

Words written

213

Sentences

Lessons live

Exercise types

Grammar pages

350

Words, target

Chapters 1–5 are finished and playable. The other fifteen are planned, in an order that took a while to get right.

The build

Ten steps, in the order they happened.

Each one had to work before the next one could start. Nothing here was bought or downloaded as a course — it's all data and rules.

Research

Take Duolingo apart first.

19 screenshots pulled apart into colours, type, corners, shadows
A screen recording turned into a written motion spec — timings, easings
15 exercise types catalogued. Nine kept at first, twelve in the end
Decision: no hearts, no lives, no timer. A lesson can't be lost

Primary green#58CC02

Button press4px down

Correct panel#D7FFB8

Tile tap140ms

Wrong#FF4B4B

Answer sheet in220ms

Corner radius16px

Progress bar250–400ms

A sample of what came out of the teardown. The whole thing became a design file the app reads from, so nothing is a guess later on.

Design system

One file decides how everything looks.

Colours, type, spacing and components live in one document
A script turns that document into the app's real stylesheet
Change a colour in one place, the whole app changes
Chapters get their colour automatically, from a pool of twelve

Chapter colours

Chapter 1 is green, chapter 2 is blue, chapter 3 is orange, and so on. Add a chapter and it picks up the next colour on its own — the path, the banner and the level buttons all follow.

Data model

The app stores words and sentences. Not questions.

Every word in every sentence is tagged: which word it is, what form it's in
From that, the app builds the questions itself — thousands of them
Two separate validators check the structure and must always agree
Wrong case endings are tolerated. Broken exercises are not

sg · nom

yra

būti

pres · 3

mano

indecl

draugė

sg · nom

turns into

Build the sentence Pick the missing word Type the translation Match the pairs What do you hear?

One real sentence from chapter 2 — Ji yra mano draugė. The blue line is the dictionary word, the yellow line is the grammatical form. That tagging is what makes every exercise type possible.

Exercise types

Twelve types of exercises, generated live, on the phone.

There is no bank of ready-made exercises anywhere — not in the app, not on a server. Every question is assembled the moment it's needed, out of the word list
Each type is a recipe that runs on that list
Wrong answers are picked from the same chapter and the same word class, so they're never silly
Listening questions use the phone's own Lithuanian voice — no audio files, works offline
Pictures come from a free pictogram library, matched by a script

Build it

Match

Pictures

Listen

Translate

Missing word

Fill the gap

Type what you hear

Plus four more: pick the meaning, word → picture, picture → word, and what do you hear.

Memory

Every word gets its own clock.

One card per word — about 350 of them when the course is finished
Answer it right and it comes back later, then later, then much later
Get it wrong and it's back tomorrow
A sentence answered correctly credits every word in it

Answer draugė correctly five times and it stops asking for two months. Miss it once and the gaps close straight back up.

Learning engine

Then I read how this is actually supposed to work, and rebuilt it.

A research pass on how Duolingo's teaching engine is put together, and on what language research says about pace and difficulty. The whole structure of the course changed after it.

The shape of the course

Sectionthe whole course, 20 chapters

Chaptera topic — greetings, questions, food

Levelone circle on the path · 4 lessons

Lesson12 exercises · 2 new words · about 10 minutes

Exercisebuilt on the spot from the word list

Levels and lessons aren't written anywhere — the app works out how many are needed from the number of words in a chapter. Chapters 1–5 come out as 23 levels and 92 lessons. Twenty chapters will be roughly 80 levels and 330 lessons.

Layer 1 · whenSpaced repetitionDecides which words come back today. Reviews are weighted towards the ones closest to slipping, not just the overdue ones.
Layer 2 · how hardA ladder, 0 to 4Recognising a word is easier than producing it. A word climbs the ladder before the app is allowed to ask the hard way.
seen
recognise
pick it out
recall it
write it
Layer 3 · which typeAim for 80%The app keeps a rating for me and one for each exercise type, and picks the type where I should get it right about four times out of five. Hard enough to learn, easy enough to keep going.

2 new words per lesson 12 exercises 3 exposures per new word 4 lessons per level last level of a chapter = revision only

Deliberately gentler than the research suggests. Easier, fewer new things at once, more repetition, more lessons.

Feel

Then a pass over every screen, for feel.

56 named animations — nothing moves by accident
Word tiles fly between the bank and the answer line
Correct answers bounce, spark and stamp a tick
Its own splash screen, streak screen and end-of-lesson screen
Everything respects the system's "reduce motion" setting

Opening

Before a lesson

After it

Streak

The streak screen only appears on the first lesson of the day. It counts days, not points — there's nothing to buy and nothing to lose.

Words & grammar

Second research pass: how grammar should be taught.

Every chapter now ships with words, sentences and a grammar page
Grammar is short, in plain language, and shows the pattern before the rule
Examples are always real sentences from the lessons, never invented for the page
Chapters 1–3 were audited and rewritten: 61 words, 146 sentences

Grammar tab

Word list

Flashcards

Handbook

A desktop handbook, for when the phone isn't enough.

Same app, different address — everything the course teaches, written out in full
18 grammar topics, grouped by chapter: the full rule, more examples, contrasts with Polish, common mistakes
A dictionary of every word I've unlocked: forms, tags, real example sentences, audio
Search works without Lithuanian letters — typing aciu finds ačiū
Export to CSV or JSON, including ready-made flashcard decks

A grammar page: the verb to be, with a full table

One topic: the full rule and the table

Dictionary entry with forms and example sentences

Dictionary, one word opened

Flashcards, desktop

Flashcards run on the same engine on both — phone and desktop, one chapter at a time, Lithuanian → Polish, Polish → Lithuanian or mixed.

Still to come

What's left.

✓ Chapters 1–5 ✓ Learning engine ✓ Grammar + handbook ✓ Dictionary + flashcards ✓ Cloud backup ✓ Installed on the phone, offline Chapters 6 → 20

↻Powtórka

Które z nich to „poranek”?

Try an exercise yourself

Click around the demo on the left, learn some Lithuanian while you're here.

No way to lose

No hearts, no timer. A wrong answer goes back in the queue and returns before the lesson ends.

Hints cost something

Tap a word to see and hear it — the question then comes back at the end of the lesson.

Works offline

All the words, sentences and pictures ship with the app. Speech is the phone's own.

One user

No accounts, no ads, no subscription, no notifications, no owl.

Chapter 6 is next

Aš mokausi lietuvių kalbos.

Five chapters finished, fifteen to write
Roughly 350 words and 600 sentences when it's done
Built at home, on evenings, for one phone

Flip the card. These are real words from chapter 2 — tap the card to turn it over, and the speaker to hear it.

1 / 8

Disclaimer. Labas is a non-commercial personal project, built for one user and shown here only as a portfolio showcase. It is not published in any app store or distributed to the public, it has no ads, no paid features and earns no money.

The app is built on open-source frameworks and libraries. Its look and feel was deliberately inspired by Duolingo as a design exercise. Labas is not affiliated with, endorsed by, sponsored by or connected to Duolingo, Inc. in any way. Duolingo is a trademark of Duolingo, Inc.; all other names and trademarks belong to their respective owners and are mentioned for reference only. No Duolingo code or proprietary assets are used. Pictograms are by ARASAAC (CC BY-NC-SA), as credited above. If you are a rights holder and have a concern, please get in touch and I will address it promptly.