School bells have long been used in real classrooms to mark the beginning and end of lessons, breaks and exams, which is why the sound is recognised instantly across generations. Online, short recordings of that warning ring are reused as a simple audio cue in classroom skits, study videos, reaction clips and school-themed memes. Because it needs no explanation, creators rely on it to set a scene, signal a time limit or add a playful sense of panic, keeping it a staple sound effect for education and comedy content.