On 29 February, on a special day of a special year, within the framework of the project “RadiatIon Safety: European-Ukrainian APproach” (101127143 — RISE-UP — ERASMUS-JMO-2023-HEI-TCH-RSCH), which is being implemented at the Department of Materials Science and New Technologies of Vasyl Stefanyk Precarpathian National University with the support of the European Commission (Jean Monnet Programme – 2023), an interactive lecture and master class titled “Seeing the Invisible – Radiation Around Us”were held for first-year students of the Faculty of Physics and Technology and Ivano-Frankivsk Professional College of Vasyl Stefanyk Precarpathian National University.Students received a brief lecture on the nature and units of measurement of radioactive radiation, risk factors and biological effects. The practical component of the event was teamwork, which consisted in the construction of four Wilson cloud chambers by four groups, which allowed students to directly observe the tracks of fast charged particles as components of natural radiation flows of “cosmic” and “terrestrial” origin. The idea behind the cloud chamber is the ability of ions generated by fast particles passing through matter to act as nuclei during the condensation of droplets in supersaturated vapour.It is very important that the work of all four teams was equally successful – all the designed cloud chambersworked and allowed students to see with their own eyes in real time the passage of particles (electrons, muons) that make up the radiation fluxes that are an integral part of our lives.