Some schools probably spend too much time working on the dress code (in my day, it was the length of the girls' skirts and the boys' hair) and not enough time working on the spelling of tricky words like minuscule. A search in OhioLINK for Miniscul* gets 11 hits, making this far more than a minuscule typo—after all, the correct spelling only gets 93. Take special care to consult the source directly before making any changes (if the error occurs in a transcribed field). This is a remarkably easy mistake to make, though. The U and I keys are right next to each other; it's an extremely common misspelling; and the cataloger may have been momentarily distracted by hazy memories of miniskirts in high school.
(Prize Winners at the Wenman School in July 1970, from Flickr.)