This intrigued me -- I've been looking for a Jewish orphanage on Long Island without any success (for my grandfather and his brother, around 1922 for a year or two), and someone had also mentioned Pleasantville to me at one point, but as a children's home, not a reformatiory.

Anyway, I googled the name of the one you provided and found a rare book dealer has a 1909 diary of a teacher from there on sale. for a lot of money. I took a quick look at the 8 pages he shows (of 26) and saw a name or two specified -- might be useful to look at for clues if Pleasantville and not Plainview is what the OP ultimately decides is what's needed. 

The link is https://www.betweenthecovers.com/pages/books/425414/author-unidentified/diary-woman-teacher-working-at-the-hawthorne-new-york-jewish-reform-school-for-boys

Wendy Kalman
wendybkalman@...
Acworth, GA

Mogilev Podolsky: BERG and TEPLITSKY
Kamenetz-Podolsky: TEPLITSKY, SIMON
Pogrebische, Ladyzhyn, and Odessa: KELMANSKY
Ladyzhyn and Odessa: MALKIS, COHEN
Berdynove: BURDA
Berdichev and Odessa: KRAPEL, GERSHBERG
Tulchin: POTTEL