Offline Classroom Content Sharing over Wi-Fi Direct for Schools
A final year project that builds an Android app for teachers and students in schools with little or no internet: one downloaded lesson pack spreads phone to phone over Wi-Fi Direct and Bluetooth, and quiz results flow back to the teacher the same way. Content-addressed sync, resumable transfers and a real classroom trial.
Advanced
Needs a team, real planning, and a supervisor who knows the area.2 semesters · 3 to 4 students
7 to ship
3 optional extrasSuggested stack
What you should ship
- Lesson pack format (videos, PDFs, quizzes) split into content-addressed chunks with a signed manifest
- Peer-to-peer transfer between nearby phones with discovery, resumable chunk transfer and hash verification
- Gossip-style sync so any phone that has a pack can pass it on, and a phone only fetches chunks it is missing
- Quiz app for students that works offline and stores attempts locally
- Return path: student attempts travel back to the teacher phone through the same peer network, deduplicated
- Publisher web page where a teacher or NGO uploads and signs lesson packs
- Classroom trial with at least 15 phones reporting time to full distribution, bytes over the air and failed transfers
If you have time left
- Delta packs so an updated lesson only transfers changed chunks
- Priority rules that send small quiz files before large videos
- Simulator that models 100 phones with random encounters to study spread time
The problem schools have with digital content
Many schools in towns and villages have no reliable internet, but many teachers and older students have an Android phone. Mobile data is expensive, so a video lesson that costs a teacher a few hundred megabytes to download will not be downloaded again by 40 students. Today content moves around by Bluetooth file sharing and WhatsApp forwards: unorganised, often corrupted, with no way to know who has what or to collect quiz answers back.
The same pattern appears in refugee camps, rural clinics training health workers, and any setting where one device sometimes reaches the internet and the rest rarely do.
What already exists and the gap
- Kolibri by Learning Equality: an open source offline learning platform with peer-to-peer sync between devices on a local network, usually around a laptop or Raspberry Pi server.
- SHAREit and similar file-transfer apps: fast phone-to-phone transfer, but no structure, integrity checks or return path.
- Google Nearby Share / Quick Share: one-off sharing between two people.
The gap is a phone-only system with no local server, where structured lesson packs spread across a classroom automatically and results come back, built for cheap Android phones.
What you build
- Publisher (teacher or NGO): uploads a lesson pack on the web; it is chunked, hashed and signed.
- Seed phone: the one phone that downloads the pack while it has internet.
- Student phones: discover nearby peers, fetch missing chunks, verify, open lessons and quizzes offline.
- Teacher phone: collects quiz attempts as they flow back and shows class results.
The technically interesting part
This is a small distributed system running on unreliable phones.
- Content addressing: every chunk is named by its hash, and a signed manifest lists the chunks of a pack. A phone can accept chunks from any peer and verify them, the same idea used by Git and by peer-to-peer file systems.
- Anti-entropy sync: when two phones meet, they exchange compact summaries of what they hold (manifest IDs and chunk bitmaps) and transfer only the difference. Connections drop constantly, so transfers must resume at chunk boundaries.
- Return path: student results are small records that must reach the teacher exactly once, even if they pass through several phones. Use unique IDs and idempotent merge on the teacher side.
Show evaluators a spread-over-time chart from the classroom trial and a failure injection test where connections are killed mid-transfer.
How to evaluate it
- Time until all phones in a class hold a complete pack, for 15 or more phones.
- Total bytes transferred compared with the ideal (each phone receives each chunk once).
- Corrupted or incomplete packs after 50 forced disconnections: target zero.
- Percentage of quiz attempts reaching the teacher within a lesson period.
- Battery cost of discovery and transfer on low-end phones.
Suggested plan
- Weeks 1 to 3: study Nearby Connections, design the pack format and manifest.
- Weeks 4 to 9: two-phone transfer with chunking, hashing and resume.
- Weeks 10 to 14: multi-peer sync with summaries, first multi-phone tests.
- Semester 2, weeks 1 to 4: quiz app and return path.
- Weeks 5 to 8: publisher page, signing, teacher results screen.
- Weeks 9 to 14: classroom trial, simulator (stretch), report.
Path to a product
Education NGOs and low-cost private school networks are the first customers; they already buy content and struggle with distribution. License per school per year, or open source the app and sell hosting of the publisher plus support. Content partners can publish packs through it.
Scope warning
Do not build a full learning management system or authoring tool. Do not support iOS in core scope; peer-to-peer APIs differ. Do not attempt internet-scale peer discovery; this is a classroom-sized network.
Learn what you need on Sefism
- Mobile roadmap : Android networking, storage and background work.
- System design roadmap : replication, idempotency and consistency ideas behind the sync.
- System design cheat sheet : quick reference on hashing and consistency.
- Guide to Android app architecture : structuring the sync engine apart from the UI.
- Android developers documentation : connectivity and instrumented testing.
Get help with this idea
The sync protocol design is worth reviewing with someone before you write the transfer code. A mentor can help you cut the scope to what your team can finish, choose between the stack options above, and design an evaluation your examiners will respect. You still build it; the help is on decisions, not code.
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