first day you'll have to show proof of vaccination to enter restaurants or gyms or entertainment venues. and as cnn's athena jones reports, today is the first day that all new york city students are welcomed back in the classroom since last year. >> this is the day we have been waiting for. >> reporter: a pivotal day in new york city, as people of all ages face new requirements aimed at beating back covid-19. and many of the city's municipal employees return to their workplaces. >> you're going to remember in the history of this city, this day, september 13th, 2021, a day that was a game changer. >> reporter: proof of vaccination or a negative covid test now required at indoor restaurants, bars, gyms, and entertainment venues. with companies that don't enforce the rule facing fines. children under 12 too young to be vaccinated, will have to mask up. same goes for the nation's largest school district, where all students and teachers must be masked, as full-time