This paper shows how to use an ionizing radiation detector for practical training for students of the Department of Mathematics and Physics, Faculty of Military Technology, University of Defence. The Department of Mathematics and Physics educates future officers in technical fields, as well as civilian experts for the national security system and the defence industry. Teaching takes place in the form of lectures, theoretical exercises, and laboratory sessions. In this document, we present how students learn to apply theoretical knowledge in practice using laboratory tasks. The laboratory tasks deal with high purity germanium detectors (HPGe), which are usually used in gamma spectrometry set-ups to identify radionuclides and determine their activities in a sample.