Duolingo · Metrics · Entry · 45 to 60 minutes

Duolingo lessons per user are dropping

Duolingo is a language learning app that uses short lessons, streaks, and game like rewards to help people practice every day. Answer this product management case and get it graded line by line against a weighted rubric.

metric diagnosis
funnel analysis
hypothesis generation
prioritization
written communication

The situation

You are an APM on Duolingo's learning experience team. At the weekly metrics review, your manager asks you to investigate a confusing pattern. Over the past month, daily active users have kept rising, but completed lessons per user has fallen sharply. The drop matters because lesson completion is a core sign that users are actually learning, not just opening the app. Leadership does not want a quick fix that boosts one metric while hurting growth, streaks, or long term retention. The team also does not yet know whether the issue is concentrated in new users, returning users, certain languages, specific lesson formats, or one platform. Some teammates think recent growth simply brought in lighter intent learners. Others think something in the product experience may now be making lessons harder to finish. Your manager wants a clear root cause plan and a short recommendation before the next product review so the team can decide what to analyze first and which low effort interventions, if any, to test.

What to produce

A 1 page metrics diagnosis memo, 700 to 900 words.

Your answer must

Define the problem precisely and name 1 primary metric plus at least 3 supporting metrics you would inspect.
List 6 to 10 clarifying questions that narrow scope, user segments, timeline, platform or lesson type, and business goal.
Describe the lesson funnel from app open to lesson completion and identify 1 or 2 breakpoints you would investigate first.
Provide 3 to 5 root cause hypotheses, and for each one state the data slice, metric, or user signal that would confirm or rule it out.
Recommend a prioritized next step plan that includes analysis first, then 1 or 2 low effort experiments or mitigations if the evidence supports them.

Constraints

You have one week to present a plan to leadership.
Assume no large feature build or course redesign can ship this month.
Base your answer on data Duolingo could plausibly already have, such as product analytics, user feedback, and app reviews.

Format

Use short sections with headers. A small table for hypotheses and tests is fine.

How Duolingo actually played it

A root cause case where Duolingo daily actives rise but lessons completed per user fall. The answer pulls out the keywords and tests hypotheses on who is new and what changed.

Rising users with falling depth often means a mix shift
Check new user share and content changes
Treat volume and depth metrics together

Built from Duolingo completed lessons dropping: Root Cause Analysis case by Sreerag Panat.