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.
This is a romantic story of a young man coming of age and the special realtionships between two sets of parents, his and his girlfriend's. Like most love stories there is sex and tragedy and a wonderful relationship that develops.
His wife sent him to pick up a mattress that she had purchased. He found the mattress and a sex-starved teenager who showed him how smooth and comfortable the mattress was. That session made him late to collect his sister from the bus depot. She tasted his pussy smelling lips (no time to wash his face), and helped herself to his still sticky cock.