Grindstone Island Upper Schoolhouse

Grindstone Island Upper Schoolhouse is a historic one-room school building located on Grindstone Island, Clayton, Jefferson County, New York. It was built in 1885, and is a 1 1/2-story, three bay by one bay, frame building on a granite foundation. The building includes a vestibule and small teachers apartment. Also on the property is a contributing well pump. It operated until 1989, making it the last one-room school in operation in New York State.

It was added to the National Register of Historic Places in 2012.