Streaks
Onboarding language learners, to increase user retention.
Introduction
Babbel is a paid, subscription-based language learning app for web and mobile. Unlike many competitors, Babbel targets users who are serious about learning, and offers a more traditional experience like a textbook.
Introducing learning streaks
To support the company's retention goals, the product team decided to run an A/B test to evaluate whether users would engage with learning streaks.
A streak counts how many days in a row a user completes a learning activity. It's designed to boost motivation.
The challenge
To onboard users to streaks, the team added a tooltip to the new streak icon in the home tab. With a streak active, the tooltip appears once the user taps on the streak icon.
I was brought in early to this project to define what we need to tell users to keep them engaged and ensure they understand what streaks are.
The message needed to be short and localisable into 8 languages, which significantly limited the available space.
Competitor research
Popular education apps like Duolingo share consistent patterns:
- An upbeat, encouraging tone.
- Clear guidance on how to maintain a streak and the risk of losing it.
- Treating the start of a streak as a milestone.
These apps typically use full‑screen onboarding rather than tooltips, so I had to carefully balance how much information to include.
First drafts
To onboard users, the tone had to be encouraging and instructional.
I initially only focused on what the user should do to maintain their streak, to keep the tooltip short.
After discussing with the product manager and designer, I learned that streaks only increase with specific learning activities. This meant the tooltip needed to be more precise.
I revised the copy to mention the relevant activities, and to highlight that the user is already on a streak, I framed it as a milestone.
User research
To understand how users perceived the tooltip, I ran a small unmoderated copy test on Lyssna. I sent a design survey to Babbel's largest market, and collected qualitative feedback through 4 short questions.
To quickly share the results with the broader product team, I created a small report with the help of Gen AI.
Around 90% of the participants understood how streaks worked, so we moved forward confidently.
Localisation
The tooltip was localised into 8 languages. To keep the message concise, I asked the localisation team to stay within 3 lines of text.
Following Babbel's localisation guidelines, I agreed to use "Learning tempo" with the German linguist as the German term for streaks.
For Swedish, it was surprising to find out that no equivalent term existed in any other competitor. The Swedish linguist and I agreed not to reference streaks directly, and instead encouraged users to "keep it up".
For the rest of the languages, there were no issues localising streaks.
Impact
The A/B test had overall positive results, and streaks were rolled out to all Babbel users.
Users with streaks learned for more consecutive days. After 2 weeks, active learning days increased by 2.5%.
Streaks went on to become a core engagement‑driving feature.
15% increase
learned for 7+ days in a row
2.3% increase
first-week active learning days
“Hary has been pivotal for the success of the streaks features that we developed this year. His project management when coordinating complex translations, handling keys, and multiple projects simultaneously was impressive and made me as a designer always feel that he had it under control.”
Next steps
The limited space in the tooltip was addressed in later iterations as more streak‑related screens were designed and implemented.
Even though this began as a small A/B test, streaks ultimately became a foundational part of Babbel's engagement strategy.
More case studies

E-invoicing
Guiding users to a new feature, to increase early adoption.

AI Writing Assistant
Building a tool to help a content design team write efficiently.

Codux
Simplifying Git microcopy to foster designer-developer collaboration.

Necessary Behavior
Creating a content style guide to guide 16 content writers.