Even if no school rules were broken (there's nothing about possessing cocaine at a school-run event?), what about Miami Police Dept employee rules not allowing personal use of evidence (especially drugs)? This will be swept under the rug because the media's afraid to question the police.
...according to the article, the "scientific" part of the project was conducting at a police training facility
School-associated events generally have the same rules regardless of location, or else the school refuses to be involved. If the school's annual science fair wasn't associated with the school (huh?), that makes the science fair a police event, under police rules. Then as I said, the question is, doesn't a big police department like Miami's have any rules about its employees flashing evidence at public meetings (especially drugs)?
Possession of cocaine within 1000 feet of a school is a crime just about anywhere, and most certainly in Miami.