Using Bluetooth to transfer between devices

Bluetooth can be used to share course content and media files directly between devices, so users without an internet connection can still get updates.

For this to be possible, when a course is installed or updated in the device, a backup copy of the installation package is saved under the backup/ folder of the app.


If you had the app installed prior to the update in which this functionality was added, the courses that were previously installed will not appear in the transfer section, as the backup files are not available.

General Workflow

  1. Course content is updated or new courses are added, with new/updated media files.

  2. A supervisor or project staff member downloads the updated course/media content onto their device, when they are in an area with internet connection, or by sideloading the updated content.

  3. When the supervisor visits their health workers in an area where no internet connectivity is available, they can synchronise the updated course/media content from the supervisors device onto the health workers device, using the bluetooth Sync option in the main OppiaMobile menu.

  4. This will move all the selected content and media onto the health workers device.

  5. The health worker could then also share these updates in the same way with her colleagues.

The Sync transfer view

To access the Bluetooth sharing functionality, select the “Sync” option from the main menu. This will get you to the Synchronize view, where there are two different tabs: the “Transfer” tab to connect and transfer course contents between devices, and the “Activity” tab, related to the student activity tracking and how it gets synchronized in the server. We will focus in the first one, where you have the following components

  • The status title shows the current state of the Bluetooth connection

  • Under the status, you can see the information of the connected device

  • A button to set your device in Discovery mode

  • A button to connect to another device

Pairing Devices

To start transferring courses between two devices using Bluetooth, we need to make the Bluetooth connection them first. For this, you have to choose on of the devices to be the one that starts the connection.

If its the first time those two devices are establishing a connection, we need to pair them first. The pairing process is only needed the first time as a security measure to ensure that both devices recognize each other and grant the communication. The next time, this process can be done automatically.

Bluetooth pairing is generally initiated manually by a device user. The Bluetooth pairing process is typically triggered automatically the first time a device receives a connection request from a device with which it is not yet paired. In order that Bluetooth pairing may occur, a password has will be exchanged between the two devices. This password or “Passkey” as it is more correctly termed is a code shared by both Bluetooth devices, used to ensure that both users have agreed to pair with each other.

Even if you have a Bluetooth-enabled accessory near a Bluetooth-enabled device, they won’t be able to see each other until you put them into discovery mode. In this state, the device will be “discoverable” by other devices for 5 minutes. Note that is not need to make a device discoverable if you’ll be connecting from it. You only need to make a device discoverable if you’re connecting to it.

To make the device discoverable from within the app, press the “Discovery mode” button. A permission request dialog will appear, asking you for permissions to make the device visible. Once you press this, you can start making the connection from the other device, using the connect button in the status bar.


If both devices were previously paired, the device name should appear under the “Paired devices” list. If not, you can press the SCAN button to start scanning for Bluetooth devices:


After selecting the device, since it is the first time they are making a connection, a dialog will appear in both screens requesting you to allow the pairing process. Once this is granted in both devices, the connection will be made and the the status bar will show the name of the device it is connected to.


Transferring courses

Once the connection has been established, a list of the available courses will show up. Under each course title, you can see the total transfer size for this course, that includes the course package and the related media files. Pressing the send action to the right of a course will start the transfer process to the other device.


While a transfer is in progress, the number of files and the total size pending to transfer are shown in the status bar of the sender device. The user can select more courses to transfer, that will get queued to transfer under the current pending files. In the receiver side, the screen will show a loading message until the last transfer finishes.

After all the files are successfully transferred, the courses will be automatically installed in the receiver device