Growth
Duolingo — Flock
Learning alone is lonely — and lonely churns. Flock is an async friend-league: small groups compete across any subject on normalized weekly scores, turning friends into the acquisition engine.
The problem
Solo streaks are fragile — learning alone is lonely, and lonely churns. Duolingo's social hooks are too shallow for the friends who'd actually keep you coming back.
The problem
Solo streaks are fragile — learning alone is lonely, and lonely churns. Duolingo's social hooks are too shallow for the friends who'd actually keep you coming back.
Metric that matters
Primary: D30 retention of users in an active flock vs. control. Leading: friend-invite conversion (friends as the acquisition engine). Guardrail: pressure-driven churn from competition.
Key tradeoff
Async normalized-score leagues across any subject vs. real-time head-to-head. Chose async + normalization so mixed-level friends compete fairly — cut live battles to keep it low-pressure and inclusive.
Biggest risk
Competition can demotivate as easily as it motivates, and small/empty flocks feel dead. Cold-start: you need 2–3 active friends before the loop works.