There are tons of advice articles, how-to books, blogs, news stories (most of which involve arrest warrants) about substitute teaching. There are movies and books where the occupation of "substitute teacher" is a cover identity for a more glamorous and adventurous lifestyle. There are, however, very few books of fiction where the main character is "just a substitute teacher".
Emil DeAndreis's book "Beyond Folly" is a work of fiction about a budding poet making ends meets as a 3rd year substitute teacher in the San Francisco school district. I'm not sure how much of the work is fiction but I certainly recognize a lot of non-fictional situations as only someone experienced as a "real life" sub can attest .
Horton Hagardy has discovered that life as a professional poet does not cover both food and rent...sometimes neither. Meanwhile, waiting for fame and fortune as a poet to blossom, Horton resorts to working as a part time substitute teacher to pay the bills.
Horton is tested and re-tested while juggling to learn new skills dealing with sleep deprivation, classroom management, district office politics, coworker subs and "real" teachers.
Fame and fortune does eventually end Horton's foray into the education system but not quite the way he planned.