I don't have ideas where schools require students to wear chastity equipment because "I don't enjoy writing stories centered around an authority using laws or rules to discriminate against large group of people based on something they can't control like sex or skin color".
Three of my ideas have individuals in chastity at school, but for their own reasons:
One where a spoiled brat accepted chastity willingly but is ignoring the spirit of the deal so, several years later her mother grows desperate and puts stricter rules on her to motivate her to turn her life around. (This is one of my best ideas, but I might have to give it to one of my writing buddies. It came to me as fanfiction and, every time I try to change the idea to be original, my muse finds new reasons for it to be the fanfiction I don't want to write.)
One science fiction story where everyone wears a symbiotic body suit from birth and a shy girl orders hers to put her in chastity until she works up the courage to confront her crush.
One where a girl with a chastity fetish lives in a setting where you can spontaneously get the ability to cast magic spells that reflect your personality and your desires, and then she has to deal with the consequences of impulsively putting herself in time-locked chastity when she hasn't even told anyone she has a chastity fetish to begin with.
...and then I have other ideas which don't involve school in any way.