Online behaviour issues are usually routine issues in disguise. If pupils don't know how to enter, where to put their answers, when to unmute, or how to ask for help, you'll get exactly the chaos those gaps invite. Spend the first lesson of any online unit explicitly teaching the routines.
Common routines worth teaching: how to join the room (camera on, mic muted, name displayed correctly); how to signal a question (hand-up button or chat 'Q'); how to share work (post in chat or upload to platform); and how to leave the room cleanly at the end.
