As you can guess from the fashion choices made by the teacher and the student on the cover of this book, The Country School was first published in 1970. According to no less an authority than the Library of Congress Copyright Office, Sharon Gordon was a pseudonym.
The cover at was by Bill Edwards, a former Hollywood actor and model who found a second career as a cover artist and a third career as a licensed SCUBA instructor. Teachers seducing their students was apparently a popular subject for pulp novels, especially the novels of the 60s and 70s. Though the cover blurb suggests that the teacher is the one initiating the seduction, she’s seated in the cover while the student towers over her, which creates a skewed power dynamic. Though his face is turned at an angle, what we can see actually makes the student look older than the teacher. Maybe he’s had to repeat a grade or two.