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Explanation: What happened to my skills?

What happened?

We course volunteers have been working on creating a new tree, known internally as Tree 4. What happened on Monday was the final stage of the process of rolling out Tree 4 to all users.

What is A/B testing? How are new trees rolled out?

This process varies a bit from language to language and from tree to tree, but here’s the timeline of Tree 4:

Starting in May 2019, half of all new Duolingo Esperanto learners were given the new Tree 4, while the other half remained on Tree 3. This is a process called A/B testing, where half of users are given one version of a product and the other half are given another. Various metrics are measured to determine which tree is “better,” and after some time has passed, the Duolingo staff reaches a conclusion about which tree to keep. At the end of August, it was determined that Tree 4 outperformed Tree 3, and Tree 4 became the default tree for all new learners. In September, the same process of A/B testing Tree 3 vs Tree 4 began for existing learners, which is what caused the exact same issue in September. The experiment was recently deemed successful, and on Monday everyone who was not moved to Tree 4 in September was moved to Tree 4. Everyone is now on Tree 4.

What’s the problem?

When new words are added to a skill that you have already completed, some progress (in the sense of percent complete) is inevitably lost, as these skills now have some content that had no equivalent in the old tree. Duolingo currently doesn’t have any smoother way of transitioning people from one tree to another besides removing progress from skills that have been changed in any way between the two trees. We cannot do anything about this; while we were responsible for the differences between Tree 3 and Tree 4, the execution of how people are transitioned from the old tree to the new tree is out of our control.

What’s the point? What’s the difference between Tree 3 and Tree 4?

Most of the new developments in Tree 4 are under the hood. Duolingo recently created a new system that allowed us to create compound words without having to add these words individually to the course. This system is excellent for a language like Esperanto with many prefixes and suffixes; transitioning over to this system has had and will continue to have lots of organizational benefits for the behind-the-scenes of the course. Additionally, several words were moved around from one skill to another for pedagogical reasons, improving skills where people struggled in Tree 3. Some of these skills were split into multiple skills in Tree 4. However, there were also a few changes in the contents of the course. A few problematic sentences and words were removed, and a few new words and sentences were added.

How can I fast-track getting my tree back to how it was before?

If you previously had completed the tree, completing the checkpoint at the bottom of the tree will raise all your level 0 skills to level 1 in one swoop. Click the tower labeled “4” at the bottom of the tree to get started. After this, you can use the test out feature to level up individual skills. Click on a skill and then click on the key button to test out of the current level of that skill. This is much faster than manually redoing each skill to level it up normally. Note that Duolingo has different functionality from one platform to another, so if you aren’t able to do this in the app, try using your phone’s browser or a computer.

Where can we hear from you?

Some of the other contributors are a bit more responsive on the Duolingo Esperanto Learners Facebook group, which I highly recommend joining anyway for lots of great discussion, many expert speakers, and tons of resources. I tend to be more active here in the forums. Major course announcements (e.g., re: tree updates) are posted on the incubator page, though we can post them here as well going forward.

Final Comments

We totally understand how frustrating this is and really wish it didn’t have to be this way. However, do keep in mind that what matters the most is not meaningless internet points, but learning Esperanto and having fun while doing it. Just because you lost your golden owl doesn’t mean that you suddenly forgot all of Esperanto!

This may also be a good time to evaluate if Duolingo is still the right course for you. If you were nearly done guilding all your skills, you might be beyond the level of Duolingo. If this is the case, you’re probably at a stage where you would learn more from reading books in Esperanto, talking to people in Esperanto, watching videos in Esperanto, and actively using Esperanto. Check out afterduolingo.com for some good resources.

We are sorry for any inconvenience that this has caused. We hope that you can enjoy the new Duolingo tree and remember that you are more than your crown count on Duolingo. :)

November 27, 2019



Dankon. Mi aprezas vian laboron. Dankon por enkonduki min al Esperanto ;).


Thank you!

I finished tree 1 and took a break from Esperanto. When tree 2 came out I used it as a way to refresh my memory. I finished half of the new skills in tree 3 and I'm looking forward to making it through tree 4.

My skills were reset, but my memory wasn't. This will be fun.


Great, at least we have an explanation. It would've been better if we had any idea this would happen someday though. Thanks for your work and your time!


Thanks for taking the time to write-up such a detailed explanation! Hopefully Duolingo will get better mechanisms to migrate progress in the future.


Ah! Mi komprenas, dankon pro vian laboron!


dankon pro via laboro! (sen akuzativo)


Ah dankon, mi estas komencanto :)


Thanks for all your hard work team! :)


It would be better if getting through a tree wasn't tedious.

Also the lesson bits need to be visible on smartphones, rather than being real-computer only.


I also really wish Tips and Notes were available in the app! Fortunately the fine folks at duome have put together this webpage with our Tips and Notes. Other language courses’ T&N are available there as well.


Dankon por la klarigo


Dankon por viaj laboro!


Dankon por viaj laboroj! Dankon por via laboro!


Hi Esperanto Team, are there any plans to eventually lengthen the tree to add more lexemes, or to add stories and podcasts?


I'm not on the Esperanto team, but I am on the Latin team. Contributors have no access to the stories or podcasts. The staff is in charge of both of those things.

Though I'd love to see Esperanto versions of each. :)




Do you guys have any prediction when the new tree will come to duolingo from portuguese?


That's a totally different team.

If you wanted an ETA for Latin I could tell you that's at least nine months away. Portuguese? No clue ;)


Thanks for the hard work and the explanation!


When I click on:

Duolingo Esperanto Learners Facebook group

This seems to lead to a
foreign web site. I am
logged out and it will
not recognize my account.

I cannot find it on the
Duolingo web site.

Thanks in advance.



Search "Duolingo Esperanto Learners" in Facebook.


Are you talking about the
Marc Zuckerberg website, or
is this on Duolingo?

Thanks for your help!



The Mark Zuckerberg website is Facebook. That's the website of the link that you posted.


Thanks. I do not believe that any prudent
person should use that website. Does
Duolingo ignore that perspective for
those of us who need to give feedback and
see the discussions?

Thanks for the great response.



You do not by any means have to join the Facebook group! The forums here are also a great place to ask for help. :)

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