Live online class

A live online class is a class in which a teacher teaches over video in real time, and the students join from their phones or computers, wherever they are. The students see and hear the teacher as the teacher speaks. They can ask questions in a chat window, answer quick polls, and in a small class they can turn on their microphone and ask the teacher directly. Most classes are also recorded, so a student who missed one can watch it later. Because the class reaches students over the internet, one teacher can teach a few students, or lakhs of them, at once.

Here is how it works in general. The class software captures the teacher's camera, microphone and screen, or a digital whiteboard on which the teacher writes. It sends this video to servers, which copy it to every student who has joined. The students send back chat messages, poll answers and raised hands. In a large class, teaching assistants read the chat, answer most of the questions themselves, and pass the most common ones to the teacher. When the class ends, the recording is stored for the students of that batch.

The size of the class decides the technology. A small class, such as one tutor and one child, uses two-way video, as in a video call, with less than a second of delay, so that the two can talk naturally. A class of thousands is sent more like a live cricket stream, with a delay of a few seconds. That delay lets the servers send the same video to every student, and change its quality to suit each student's network speed. This technique is called adaptive bitrate streaming. The students in such a class cannot all speak, so they use the chat and the polls instead.

Take, for example, a JEE batch on an online coaching platform. One physics teacher teaches tens of thousands of students in the evening, and a poll shows within seconds how many of them understood the last problem.

Consider a parent who books coding lessons for a ten-year-old. In online classes for kids, one teacher teaches one child, or a small group, over two-way video.

Say a working engineer joins a cohort-based course. The group meets live twice a week for some weeks, and the fixed sessions keep everyone moving at the same pace.

How is a live online class different from a recorded course? On an online course marketplace, the lectures are recorded once, and each learner watches them alone, at any time. That is cheaper and more flexible, but nobody answers a question during the lecture. A live class happens at a fixed time, and the teacher can respond to the students while teaching. Many courses combine both: a live class, followed by its recording.