The ringing of the bell to signal the beginning and end of a class period, rather than just the beginning and end of the school day is often traced to William Wirt, who became superintendent of schools in Gary, Indiana in 1908.

Bells, primarily handbells, have been a technology of school since their outset, well before "the factory" they were purportedly modeled on. They were used, as were the bells in churches, to summon students to ye old one room schoolhouse for the beginning of the day.

He was, after all, one of the most influential promoters of the "school-as-factory" narrative: that the origins of mass schooling are inextricably bound to the need to reshape a rebellious farming nation's sons and daughters into a docile, industrial workforce.

I'd wager it's the most frequently told story about ed-tech — one told with more gusto and more frequency even than "computers will revolutionize teaching" and "you can learn anything on YouTube." Indeed, someone invoked this story just the other day when chatting with me about the current shape and status of our education system: the school bell was implemented to acclimate students for life as factory workers, to train them to move and respond on command, their day broken into segments of time dictated by the machine rather than the rhythms of pre-industrial, rural life.