At a glance
- Client / partner
- edX Platform
- Industry
- EdTech
- Services offered
- Dedicated Engineering Pod
- Web & Mobile Development
- Data & Analytics
- Platform Engineering
- Tech stack used
- Video streaming
- React
- Mobile clients
- Event telemetry
- Offline sync
- Analytics pipeline
edX is an online learning platform delivering courses to learners around the world.
A Zemotify pod worked on interactive video learning infrastructure: real-time learning telemetry, gamified lessons and offline sync for learners with unreliable connections.
Introduction
Video is the heart of online learning, but watching is not the same as learning. Platforms need to know where learners pause, rewind or drop off, and lessons need moments that ask the learner to do something, not just watch.
Learners also study in places where connectivity can’t be taken for granted. A lesson that stops when the signal drops is a lesson that doesn’t get finished.
The goal was infrastructure that made video interactive, measured engagement as it happened and kept learning going offline, without making course authors’ lives harder.
The challenges
Interactive video at scale raises problems that a simple player never has to solve:
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Telemetry without slowing playback
Capturing play, pause, seek and quiz events in real time can’t add buffering or drain batteries on lower-end devices.
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Interactivity inside the video
Questions, checkpoints and branching moments had to be authored once and behave the same on web and mobile.
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Motivation that isn’t a gimmick
Gamified elements such as streaks, progress and rewards needed to support learning goals, not distract from them.
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Learning offline
Lessons, quiz answers and progress recorded offline had to sync back reliably, without duplicates or lost work.
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Turning events into insight
Raw interaction events are only useful once instructors and product teams can read them as trends and drop-off points.
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Learner privacy
Engagement data is personal data. Collection, retention and access had to respect privacy expectations from the start.
The approach
We treated the lesson as an event-producing application rather than a video file:
An interactive lesson runtime
A shared lesson format describes video segments, questions and checkpoints, rendered by the same runtime on web and mobile so behaviour stays consistent.
Lightweight real-time telemetry
Events are batched on the device and streamed when the connection allows, keeping playback smooth while dashboards stay current.
Offline-first sync
Lessons can be downloaded ahead of time; progress and answers are stored locally and reconciled with the server when the learner reconnects, with conflict rules that never lose work.
Gamification tied to learning goals
Progress, streaks and achievements are driven by meaningful actions such as completed checkpoints and correct answers, not just minutes watched.
The systems behind each lesson
How video, interaction and data come together for one learner.
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Lesson Runtime
One lesson format for video, questions and checkpoints on every platform.
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Event Telemetry
Batched, low-overhead interaction events streamed in near real time.
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Offline Store
Downloaded lessons and locally saved progress that sync safely later.
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Progress & Rewards
Streaks and achievements driven by real learning actions.
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Analytics Pipeline
Events modelled into engagement and drop-off views for course teams.
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Privacy Controls
Retention, consent and access rules applied to learner data.
Insight for course teams
Engagement views show where learners rewatch, skip or leave, so instructors can improve the lessons that need it most.
Built to be observable
Telemetry for the platform itself, covering sync failures, playback errors and slow segments, so issues are found before learners report them.
Delivery alongside the in-house team
The pod worked in the client’s sprint rhythm, with shared demos and documentation so the platform team could own it long term.
The outcome
Outcomes are described qualitatively until verified figures are confirmed with the client:
Interactive lessons: video lessons with built-in questions and checkpoints across web and mobile.
Engagement you can see: near real-time telemetry turned into views course teams can act on.
Learning that survives a lost signal: offline lessons and progress that sync back without lost work.
Motivation by design: gamified progress tied to completed learning, not screen time.
- Pending verification
Learner engagement
- Pending verification
Lesson completion
- Pending verification
Offline sessions synced
Technology used
An illustrative view of the toolchain used for this kind of build (to be confirmed with the project team):
| Web & Mobile | React, native mobile clients, shared lesson runtime |
|---|---|
| Video | Adaptive streaming with interactive overlays |
| Telemetry | Client-side event batching, streaming ingestion |
| Offline | Local storage with conflict-aware sync |
| Analytics | Event warehouse and engagement dashboards |
| Engagement | Progress, streak and achievement services |
| Privacy & Ops | Consent and retention controls, monitoring and alerting |
