Environmental radioactivity is all around us. The public imagination often associates a negative feeling to this natural phenomenon. To increase the familiarity with this field CAEN designed a dedicated educational kit, based on Silicon Photomultipliers (SiPM) matrix coupled to a CsI Scintillator. Teaching and training experiences are performed starting from system calibration in terms of energy and by acquiring gamma spectra to study the emission and the composition of different samples.