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Case studiesKhan Academy
Khan AcademyEdTech / Non-profit Learning2025

Adaptive mastery-streak nudges for learner retention

Khan Academy's mastery streak is one of the most loved features in online learning — and one of the easiest to break the moment a learner has a hard week. We built an adaptive nudge layer that personalizes lesson length to a learner's energy curve, lifting 14-day retention 19% for opted-in cohorts.

14-day retention
+19%
Learners enrolled
~1.2M
Personalization latency
<60ms
Languages live
12
kKhan Academy/ Maya R. · Grade 9
🔥 17-day streakContinue learning →
17day streak

Good morning,

Maya

You're ~12 minutes from today's goal. Pick up where you left off.

Mastery 74%·XP today 0 / 60·Energy medium

Today's plan

Adapted to your energy curve
Algebra~6 min

Solving systems of equations

Biology~5 min

DNA replication review

History~4 min

Renaissance: finish unit

Subject mastery

7-day trend
Algebra
74%
Biology
62%
World History
89%
US Government
41%
Statistics
28%

Khanmigo noticed something

Yesterday you got stuck on quadratic substitution. I queued a 4-minute warm-up before your Algebra lesson today.

Try the warm-upSkip for now

Recent quiz scores

Linear systems

Today · 7:42 am

9 / 10

Cell respiration

Yesterday

7 / 10

Industrial Rev.

2 days ago

10 / 10

Polynomial factoring

3 days ago

5 / 10

Badges

12 of 48
🌱Sprout
🔥On fire
🧠Quick
🪐Cosmic
📐Geom
🧬Cells
🏛️Empire
🎯Sharp

Class assignment

From Ms. Chen

Quadratics: word problems

Due Friday · 12 questions

3 of 12 complete

The brief

The mastery streak is Khan Academy's quiet superpower — a daily learning loop that millions of students use to stay on track. It is also fragile. A student has a busy week, the streak resets, and the system has just penalized exactly the kind of week that needed gentler scaffolding, not more pressure.

The bet: an adaptive nudge layer that personalizes lesson length and mix to each learner's recent energy curve would protect the psychological benefits of the streak without punishing the messy weeks that life actually involves.

What we built

A real-time personalization service that scores each learner's "energy curve" — recent session length, accuracy, breaks, time-of-day patterns — and recommends a daily plan calibrated to what they will probably complete, not what an idealized version of them would. The service returns a plan in under 60 milliseconds, well inside the page-load budget, and is updated continuously as the learner progresses.

The Khanmigo integration was small but important: when a learner is visibly struggling on a recommended item, Khanmigo proactively offers support instead of waiting for the learner to ask. The threshold for "struggling" is itself learned from the learner's own history.

We launched against a tightly-bounded A/B with strict guardrails: no suggested plan can be shorter than what the learner has demonstrated the ability to complete; no streak can be silently extended. The system recommends, the learner decides.

Outcome

14-day retention for opted-in cohorts lifted 19% versus the control. ~1.2 million learners are now enrolled. The personalization service is live in 12 languages.

The most quietly important outcome: cohorts with previously-broken streaks recovered them at a meaningfully higher rate after the launch — the system is doing what it was designed to do, which is to help learners come back after the hard week instead of giving up.

"We did not want to gamify the kid into doing more — we wanted the system to meet them where they were."