Public school students have officially said goodbye to summer and kicked off a new school year. 

The first day back also marks the launch of the city's universal pre-K program, which Mayor Bill de Blasio is calling a day that will go down in history. More than 50,000 youngsters have now started their education early as part of his signature initiative. 

De Blasio even made a stop at Inner Force Tots in Brooklyn to help teachers welcome kids to their new classroom.

The mayor and schools Chancellor Carmen Farina have been making their way around the boroughs visiting students at various schools.