Why did my course change? 

So you get a notification one day that there’s been an update to the Duolingo course that you’re in. Naturally, you’re probably wondering — what sort of update? What’s changed? And why? Read below for a bit of information on Duolingo’s iterative and experimental approach to building language courses...


Why are courses updated?

There is no such thing as a “finished” language course. So at Duolingo, we’re always working to make our courses better! If you’ve gotten an update, it’s because we’re excited to share the latest changes to the existing course.


What kinds of improvements happen in a course update?

  1. Additional content: Our goal is to teach the language you’re learning through B2 on the CEFR scale. So we may have added more content to get you closer to the B2 level!
  2. Adjusting existing content: We’re running experiments all the time testing to see how we can teach most effectively. We might be updating your course to tweak the content to help you learn better and more completely.
  3. Making totally new content: We want to align all our courses with the standards of the CEFR. So sometimes there’ll be a total change of your course content to improve what we teach and when, so you learn the right things at the right time.


What’s the CEFR?

CEFR stands for the Common European Framework of Reference for Languages — basically, it’s a set of standards that lay out what people should be able to do at certain points in their language learning. By aligning our language courses with CEFR standards, we’re making sure that you’re learning what’s most useful for you, so that you can learn to communicate as effectively as possible.


As mentioned above, the ultimate goal is to get all learners to the B2 level. That’s because once you’re at B2, you have all the language you need to launch a career using the target language. We want to get you to a place where you can live a full life using the language you’re studying! (Well, maybe you couldn’t get that many job opportunities using Klingon. At least not until we’re a little better at space travel.)


You can read more about CEFR levels and Duolingo in this blog post.


What happened to my skills and levels?

Changes to the content sometimes also come with changes to the skills and levels in your course. This is because we are often adding brand new content, and also because we end up moving material around to improve learning (teaching some things later, and teaching new concepts earlier in the course based on patterns we see in our learning metrics)

This can of course “mess up” the appearance of your skill levels and course colors. We understand it can sometimes feel like we simply erased progress, but this is not the case. When we are offering something new in the language you are learning, we want to give you the opportunity to see it and review it. For example: if we add new vocabulary to the “Greetings” skill, then we add new sentences. This means you have not yet seen that material and this is now a new “Greetings” skill that needs to be learned (and it might still contain sentences and vocabulary from the old Greetings skill). In short, new and revised skills popping up in your course are a consequence of our efforts to make your course richer, and your skills more robust.


What exactly is changing in the update? 

What will be changing depends on the exact nature of the update you’re getting. Most likely, however, you’ll be getting a lot of new words to learn and new lessons that focus on building up your language skills for communication.


I don’t see a difference, when is my course changing?

Maybe you’ve heard from other people that their course changed, or you’ve heard that we are “rolling out” a change, but you don’t see anything different about yours. The short explanation here is that we give the updates to a small group, and then start releasing it to more and more people if the changes are showing positive results.

The slightly more technical explanation is that this happens because we follow a procedure called “A/B testing.” A/B testing is where we divide our learners into groups, then give the first group the new version of the course and the second group the old version of the course. Then we compare how much these two groups are learning and how much they seem to be enjoying the course. If you don’t see any change to your course, it’s quite likely that you’re in our control group, and will likely see the new version in the near future. 


I got new course content, but then it went away!

Yep! That happens sometimes. When we run these A/B tests, the new version of the course doesn’t always have the results we were hoping for, meaning this is not a better version of the course in question. When that happens, we’ll move people back to the previous version of the course (so they can continue learning on the best version). Then we’ll tinker with the course, swat any bugs we might find, and try again with a new experiment.