Site: duolingo.com

Type: Education, Languages

Duolingo is a language learning platform that offers free courses in several languages. Each offers grammar and vocabulary in a structured way up to roughly intermediate command of a language. The learning process features spoken sentences, multiple choice questions, typing tests, listening tests and pronunciation tests with voice recognition.

Duolingo also offers apps for Android and Apple devices. The general idea is apparently to have the complete feature set in all incarnations of the platform, but sometimes new features or designs are rolled out on one platform before the others.

This article is mainly about the website, your mileage may vary if you use one of the apps exclusively.

Available Languages

Duolingo's course offerings are grouped into language pairs. For English speakers the currently available courses are Spanish, French, German, Italian and Portuguese. For speakers of other languages the selection varies a lot and many courses are still in their inception phase in the incubator. For numerous languages English is also available as a foreign language course.

With the involvement of the community many courses are currently being worked on and there are plans to extend established courses beyond intermediate level. It looks like Duolingo will feature many more languages courses in the not so distant future, among them not only European flavors, but languages from all over the world, including Chinese, Japanese, Korean and Arabic.

Home View

The material of the individual language courses is organized in a skill tree where successfully finishing a row of skill unlocks the row below and so on. Each skill represents a thematic unit, like food, animals or basic adjectives and is furthermore divided into lessons containing just a handful of new words and grammar concepts. This makes it very easy to have clear goals for study sessions and serves to keep a good overview of the learning progress.

For learners who already have some knowledge of a language, there is the possibility to test out groups of skills at once and thus to skip the slow introduction of the contained material. If such a test is successfully passed, all skills belonging to it are activated as if they had been learned the regular way.

Skills have a strength indicator in the skill tree consisting of five divisions. If the overall strength of the words in a skill is high enough (full indicator), that skill is shown in gold in the skill tree. As the strength of the contained words decrease over time, the strength indicator goes down accordingly. Since the indicators are a summary overview, it is possible that individual words from a skill are actually much less well remembered.

To the right of the skill tree is the progress meter, it shows accumulated experience points, the progress towards the next proficiency level and the total number of words that have already been introduced in the course. Below is the “strengthen skill” function, this global testing routine gives preference to words with lower strength and using it regularly should keep all learned skills on the upper strength levels. It is generally a good idea to use it in combination with the individual skill tests.

Below the progress box sits a box that shows friends you have on Duolingo and your performance relative to them, either weekly, monthly or all time. If you are keen on competing with other people and get motivation out of this, it's a good idea to invite some friends or to befriend some learners through the forums.


Once a learning session is started Duolingo tests on a series of sentences that are made from exchangeable elements. For example the sentence “I like the red dress” has a noun and an adjective that are each selected from a list of word candidates. Depending on what the user has already learned the sentence might also be “I like the black cat”, both noun and adjective have been exchange while keeping the predefined sentence structure.

For each word that has been introduced to the learner Duolingo keeps track of the “strength”, which is derived from the last a time a word has been seen and how the user performed when it was tested. Words with lower strength are given preference and are more often included in the sentence constructions.

In that fashion Duolingo rotates through the different test types for 20 sentences, an indicator in the upper left corner shows the progress of the session. There are three hearts in the upper right corner, for each wrong answer one heart is deducted. If you run out of hearts before the end, the learning session is terminated prematurely.

Generally it's good practice to do multiple learning sessions each day, studying a little regularly is much more effective for the learning process than doing prolonged study sessions every once in a while. A good goal is to keep all skills in the full gold state and to do additional repetitions for the problematic skills.

That being said, Duolingo's spaced repetition model has some obvious problems that will sooner or later interfere with your vocabulary memorization. Namely it has a tendency to bring up certain words too often while others are rarely to bee seen. For that reason I highly recommend using a separate program or website for long term memory effects. Memrise and Anki are good choices.

Test Types

The learning sessions employ various test types. This does not only give some variety to the practice, it also serves to boost words and their memorization from different angles.

Multiple Choice: Presents a sentence and three answering options. It's important to note that more than one can be right at the same time and the correct solution is to select all right answers. Also the differences between the three options are sometimes quite minuscule, it's therefore important pay close attention before picking. The answer(s) can also be selected by pressing the matching number keys.

Very rarely the multiple choice tests also involve pictures where the task is to correctly identify what's being shown. This is so seldom though, it seems to be either an afterthought or a relic from the beginnings of the course development. Either way it doesn't add much to the learning process.

Sentence Translation: Here you are given a sentence, either in your native language or in the language you are learning, for translation. The answer parser is relatively flexible and will generally allow various possibilities of correct translations and generously look over minor typing mistakes too. For example a French sentence starting with “je vais…” might be translated as “I go…” or “I am going…” and both will be accepted. Likewise equivalent expressions for nouns and adjectives will usually be fine. If the target language involves diacritical marks, like French accents or German umlauts, answers are still valid if you omit them, you will just be shown a helpful reminder in those cases. Also, if a correct answer was entered that was not the expected main translation, the alternative will be shown as a hint when the input has been checked.

Hovering the mouse over a word of the sentence to be translated displays the translation for that part in a tooltip. This is handy when you are just missing a single word but are confident about the overall structure of a sentence. Invoking those tooltips reduces the strength score of the word in question behind the scenes and it will consequently appear more often afterwards.

Listening Practice: During the listening tests a synthesized voice speaks a sentence in the language you are learning and you are required to type it out. The spoken sample can be repeated as often as necessary (keyboard shortcut CTRL-SPACE) and also be invoked as a slow word-by-word version (SHIFT-CTRL-SPACE).

The problem with this test type is that the synthetic voice is far from perfect, most of the time not even in the realm of good enough. Even native speakers probably would have trouble to understand what is being said. Due to the nature of the flexibly constructed sentence it's understandably well-nigh impossible to have real speakers record each and every possible variation, but the voice synthesizer being used still leaves a lot to be desired and is hardly state-of-the-art.

Thankfully this kind of test can be completely disabled in the user preferences as follows: at the very top of the screen click on your user name, then settings, here set “speaker” to off and don't forget to save the changes.

Speaking Practice: This test gives you a sentence to read aloud and the voice recognition will judge if you did well enough. Of course the usefulness of this exercise relies largely on the quality of the recognition algorithm, as well as your microphone and possibly the background noise level. In my experience it falls short of expectations and I would recommend to turn it off as well. To that end go to settings, set “Microphone” to off and save.

Points, Lingots and the Store

Duolingo awards experience points (XP) for each completed practice session. The completion itself grants 10 XP and each remaining full heart grants another XP, so a maximum of 13 XP per session is achievable. The points count towards skill levels that give a gamification incentive to strive for persistent practice. As is typical with game-like skill levels, each level further down the road requires more points than the previous, but unlike real games Duolingo's XP rewards stay constant.

Additionally there are special trinkets called Lingots. Level-ups award one Lingot multiplied by the new level, a perfect learning session with three full hearts awards one, finishing a new skill grants two, learning streaks grant one for each streak of 10 days (two for 20 etc.), and finally inviting new people to join Duolingo grants one Lingot as well. Lingots can be used in the Duolingo Store to “buy” various items. This is a nice and playful addition that introduces some more gaming elements to the learning experience.

Store Items

Heart Refill, 4 Lingots: Refills one of the three hearts during a learning session. This can be very useful if you have already lost some heart power to mistakes, but think you can still make it to the end with a little more leeway at your disposal. Use this strategically, don't waste them if you are really bad in a lesson and have already made mistakes right from the start, this probably means you won't make it through a session anyway and the refill was for nothing.

Streak Freeze, 10 Lingots: Keeps your learning streak intact even if you skip one day, activates automatically in such a case. If you like seeing that number besides your streak counter going higher and higher, this is what you want to have. It's worth pointing out that you can only have one Streak Freeze at any time and it only protects from single-day flunks.

Timed Practice, 10 Lingots: Activates a practice session against the clock. This is a nice break-out from Duolingo's normal learning routine. Recommended if you know your stuff and are looking for an additional challenge from time to time.

Double or Nothing, 5 Lingots: The five Lingots are actually a wager in a bet on your ability to keep up a streak of seven days, counting from the day of activating this in the store. If you are successful and maintain that streak of seven, you get back 10 Lingots, if you fail your 5 Lingots are gone. This can be a good motivator and an easy way to gather some additional Lingots at the same time.

Language Certificate, 25 Lingots: A virtual (and virtually worthless) certificate of your language skills that you get after a short test. Can be done at any point during your learning odyssey and as often as you like, but really, what's the point?

Bonus Skills, 20 Lingots each: Unlocks special skills with collections of special vocabulary, e.g. idioms or holiday related verbiage. Does what it says on the tin.


The forums can be found under “Discussion” in the top bar. There is a general section, one for troubleshooting and separate sections for each language. If you have questions about the site in general or about specific language problems, the answer can usually be found here. The search function quickly digs up appropriate threads and of course new discussions can be started too. The Duolingo staff is also quite active in the forum, they often post news about ongoing development, progress updates from new courses being created in the incubator and help out when problems occur.

Additionally to the global discussions, each sentence you encounter during study sessions has its own micro forum. The link will appear below the test testing area after you have answered a question. People often discuss the grammatical constructions there and it's worth checking them it out, if you are left wondering why you have failed a particular test.


In the immersion section users can use their acquired language skills to translate articles and text passages in a concerted community effort. The texts are from Wikipedia or from people who want them translated for further publishing, when the community translation is done and has been checked, they receive the final output. For commercial translations Duolingo receives a fee. This is how the platform generates income and in turn keeps it free to use for language learners.

By using the immersion part of Duolingo, participants thus not only help the site's development, but can also practice on real world documents and receive feedback from others. It's a win-win situation and the interface makes it very easy to participate.

In the upper right corner is the progress box where your immersion efforts are tracked separately from the language learning. Similar to the study sessions, translating sentences for immersion grants XP, the exact amount depends on the length of each sentence. You will also see the number of received upvotes and downvotes for your translations here, as all submitted translations are double checked by others.

Below are various options to filter displayed articles by their translation progress, difficulty and category.

The articles themselves are represented in the translation view in a color coded fashion that shows which sentences have already been translated, which need checking and which are finished. Clicking on an untouched sentence brings up a window that allows to enter the translation and also offers a machine translation for reference. Furthermore a comment can optionally be included if you feel your work needs further explanation. Sentences that have already been translated by someone else can be approved, objected or edited for further checking. Hovering over any word shows a dictionary tooltip which is very handy even for advanced learners.

The proofreading view shows original and translation side by side for better comparison and there is also a discussion section for each article.

Once a certain command of the grammatical structures of a language has been build and the vocabulary knowledge reaches a sufficient amount to at least hold every-day conversations, Duolingo's immersion can be a highly effective learning tool.


Duolingo's real strength lies in the teaching of reading and writing skills. While the listening and speaking tests don't live up to their potential, the core strength of the study sessions is the practice with example sentences made from exchangeable pieces.

Language acquisition through examples is a very effective way of learning, because it quickly conveys how to use learned words to construct meaningful sentences. Duolingo's example generation is basically a way to mutate grammatical presets which does not only deliver more variety than static constructions, it also enables the targeted introduction of new vocabulary within known patterns and a sensible repetition of previously seen material. Duolingo's scheduling logic for repetitions is arguably not the best though and the use of additional memorization tools is advisable.

Duolingo's major shortcomings are that it does little to foster spoken conversational skills and grammatical explanations are quite sparse. Users are largely left to figure out underlying rules by themselves through deduction from the examples. For that reason, it is highly recommended to use additional study material and courses as necessary. Within the scope of written language practice though, Duolingo is an effective way of learning.

Education | Language_and_Linguistics | Learning | Non-Fiction | Companies

QR Code
QR Code duolingo (generated for current page)