Duolingo · Product sense · Mid · 45 to 60 minutes

How should Duolingo use social to deepen habits?

Duolingo is a language learning app that helps people build a daily habit through short lessons and streaks. Answer this product management case and get it graded line by line against a weighted rubric.

product sense
prioritization
experimentation
metric design
strategic judgment

The situation

You are a PM on Duolingo's core learning team. Your director asks you to recommend whether the app should invest in a social feature to help more learners come back and complete a lesson each day. Duolingo already has friend connections inside the app, and 57 percent of users have at least one friend there. At the same time, the product works best when people maintain a personal learning habit, so any social mechanic that distracts from lessons, creates unhealthy pressure, or only helps a narrow slice of users could backfire. Why now: the friend graph has become meaningful enough that leadership wants a clear point of view on whether social should play a bigger role in retention, and the team can only back one meaningful habit initiative this planning cycle. Assume the team can ship one medium-sized feature or a small set of experiments in the next two quarters. You need to propose what problem to solve, whether social is the right lever, and how you would test success while keeping the focus on learning.

What to produce

Write a 1 page product strategy memo, 700 to 900 words.

Your answer must

Define the product objective, the target user or users, and why this retention problem matters now.
Assess whether Duolingo's existing friend base is large enough to justify a social investment, and state any assumptions you make.
Recommend one primary direction, social or non-social, and explain how it strengthens the core daily lesson habit rather than just increasing app activity.
Describe an MVP and experiment plan, including the primary success metric, the comparison group, and at least two guardrail metrics.
Identify the biggest trade-offs and risks, including how your plan affects users who do not have friends in the app and any negative social pressure concerns.

Constraints

Use only information in this prompt, and label any extra numbers or segments as assumptions.
Stay within Duolingo's existing app and current friend connections.
Optimize for daily lesson completion and habit strength, not generic social engagement.

Format

Use short sections such as problem, users, options, recommendation, experiment, metrics, and risks.

How Duolingo actually played it

A Duolingo PM shares lessons from building Friend Streak, a social feature that lets people share a streak with up to five friends; learners with one are 22 percent more likely to complete their daily lesson. The post grounds the feature in the fact that 57 percent of users have a friend. A good case on building social features inside a habit product.

Build social features when the base of connected users is large enough
Use the core habit as the shared goal
Report outcomes with specific lift numbers

Built from 5 product lessons we learned from building Friend Streak by Jackson Shuttleworth.