A Story in the Naked In School Universe
I don't know if Karen Wagner was inspired by this story, but it appeared shortly before she stated the genre. The author is unknown. Rather than naked kids, the teachers are naked with the (successful) intention of inspiring learning.
Brienna double dates, which means she has sex with both dates. And a few people at sex parties. Quite a busy girl, and then she realizes she's in love with several people; surprise, so was her mother.
This is the story of an unintentional interracial affair between a young engaged Denver schoolteacher/waitress and an older married Sergeant/piano player during the Vietnam War.