The California High School Cosmic Ray Observatory (CHICOS) project is a research array for the detection of ultra-high-energy cosmic rays — single subatomic particles that slam into Earth’s atmosphere with the energy of a brick falling from a rooftop. The particles produce huge showers of secondary particles when they collide with atomic nuclei in the upper atmosphere. In the CHICOS project, schools across the Los Angeles area provide a network of detector sites and a valuable population of participating teachers and students.