We don't have an historical photo collection here at OBL, but the local OB Historical Society has a bunch, I believe. In fact, in a student article that I researched in grad school, there is mention of early OB schools and such:
The Freeholder, Volume 7, No 3, Winter 2003, "The Legacy of Julia L Thurston." I do recall thumbing through a good bit of educational things there, including some old school house photos. I think you need an appointment to research there these days, though. It's no longer open-access. But lots of goodies if you can get in to peek.
Stacie Hammond
Head Reference Librarian
Oyster Bay-East Norwich Public Library