Duolingo · Metrics · Entry · 45 to 60 minutes

How should Duolingo build a daily habit?

Duolingo is a language learning app that helps people practice with short lessons. Answer this product management case and get it graded line by line against a weighted rubric.

metric thinking
product judgment
experimentation
prioritization
user empathy

The situation

Your manager, a product lead at Duolingo, asks you to prepare a recommendation for the team working on learner retention. Internal analysis shows that learners who reach a 7 day streak are 2.4 times more likely to return the next day than learners who do not. The team sees this as a strong signal that habit formation matters, but it is still unclear which product lever to use. Assume only 12 percent of new learners reach a 7 day streak, and next day retention after the first week is below plan. You have one quarter, a small cross functional team, and no appetite for a broad redesign. The question is whether the team should change something in the streak experience, the lesson completion loop, or a nearby part of the daily practice flow. The tension is that a change could raise streak related metrics without creating a stronger learning habit. It could also confuse learners, feel unfair, or weaken trust if progress no longer feels meaningful. Recommend one focused product change and explain how you would know if it worked.

What to produce

A one page product brief of 500 to 700 words.

Your answer must

Name one primary success metric and two guardrail metrics, and explain why each fits this problem.
Identify the target user segment and the specific behavior drop off you want to address.
Recommend one product change to the streak or lesson loop, and explain the causal path from that change to better retention.
Describe a simple experiment or launch plan, including hypothesis, target population, comparison approach, and decision criteria.
Call out two major risks or unintended consequences, with a monitoring or mitigation plan for each.

Constraints

Stay within the existing mobile learning experience, do not propose a full app redesign.
Scope the work to something a small team could build and test within one quarter.
Do not rely on discounts, prizes, or external partnerships.
Protect learning quality and user trust while pursuing retention gains.

Format

Use five short sections: goal, diagnosis, recommendation, metrics and test, risks.

How Duolingo actually played it

Duolingo shows that learners with a 7 day streak are 2.4 times more likely to return the next day, then describes a change that made streaks easier to keep and raised learners on 7+ day streaks by over 40 percent. The post explains the logic of the change. A compact metrics-driven product example.

Tie product changes to a retention metric
Lower friction on a core habit loop
Report the lift from the change with numbers

Built from Improving the streak: Forming habits one lesson at a time by Anton Yu.