If you are referring to academic research from 2021, "Ultraviolet schools" might refer to studies on .
: Schools like Queen's Grant High School installed UV-C systems within HVAC units to neutralize pathogens as air circulates.
The phrase appears to reference a niche or emerging topic, possibly related to machine learning (ML) applications in education (schools) with a focus on ultraviolet (UV) radiation — e.g., UV monitoring, skin safety, or disinfection systems.