teacher.js: A low-bandwidth Digital Tool for Outdoor Online Teaching

teacher.js is a web-based digital communication and teaching tool. Developed as part of the teacher.solar project one of the main requirements was to keep both the bandwidth and power consumption low. For that reason teacher.js does not make use of screen sharing by means of video streaming (which is very taxing in terms of data volume and computation) but instead implements an event-driven code-casting system, where events in the teacher’s client (e.g. user interactions causing changes in the application state) are broadcast to all other connected participants so that they stay in sync. Besides audio / voice call functionality, the application can be extended by integrating additional modules for all kinds of different purposes. Currently there are a text chat module, a presentation module, a Wikipedia module, and a collaborative text editing module. The whole software suite can run on a Raspberry Pi 4 microcomputer, allowing a teacher to be the full master of the on-line teaching platform they are using to give their courses. In comparison with BigBlueButton, teacher.js consumes significantly less bandwidth for both incoming and outgoing connections.