If you are fighting this issue in your school district, be sure to research your city, county, and state laws & codes:

For instance: https://sdlegislature.gov/Statutes/Codified_Laws/2047379

https://sdlegislature.gov/Statutes/Codified_Laws/2047393

https://sdlegislature.gov/Statutes/Codified_Laws/2047382

(4) "Harmful to minors," includes in its meaning the quality of any material or of any performance or of any description or representation, in whatever form, of nudity, sexual conduct, sexual excitement, or sado-masochistic abuse, if it: (a) Predominantly appeals to the prurient, shameful, or morbid interest of minors; and (b) Is patently offensive to prevailing standards in the adult community as a whole with respect to what is suitable material for minors; and (c) Is without serious literary, artistic, political, or scientific value;