Grammar school it was the school supply closet. In ghigh school it was the school store and, I don't know, somewhere else. All I remember is that you got a free pencil box with back to school shoes in September.
The nuns in St Benedict's pushed a local store on Tremont Ave, Frank Bee's 5 & 10. In 5th grade, Sr Charles Edwards checked our notebooks to make sure that it had a Frank Bee's sticker on it or we weren't permitted to use it in class. She changed that rule, quickly, when some parents called the school.
Usually at Al & Shirley Schwartz's stationery/toy/miscellaneous goodies store on Kingsbridge Road. . .to be exact, on the side road alongside the westbound side of the Kingsbridge Road underpass at The Concourse.