This looks like a classic case of some educational initiative getting totally warped when people retell it on social media! Chances are, it's about some project to personalize the school environment, not literally letting students pick their ringtones. Even if someone did actually suggest it, it would run into practical problems real quick.
Picture this: five different melodies blaring through the school at the same time because each class picked their own! Teachers would lose their minds, parents would complain that it's annoying. Plus who's supposed to change all these ringtones? The administration? The tech staff? They're already drowning in work. And if it's a democratic vote in each class, you'd get arguments breaking out between students over which melody is cooler, more modern, funnier.
In reality, schools *maybe* can get away with picking one or two different standard ringtones instead of the default ones, and even that's rare! Rolling something like this out school-wide? Just won't happen, because it creates way more problems than it solves.