This is a generic school bell recording rather than a clip from a specific film, show or song, which is why it works so well as a universal classroom cue. School bells have long been used in comedy sketches, cartoons and online videos to signal a change of lesson, the start of break or a return to class. On social media it is now a shorthand for school life itself, instantly understood across languages and cultures. That familiarity keeps it popular for memes, edits and short-form videos about school, exams and teachers.