We describe a group laboratory exercise in which neutron activation analysis (NAA) is used to illustrate the concepts of nuclear reactions, nuclear energy levels, characteristics of gamma rays, radioactive decay and half‐life, and Compton scattering. Small groups of 10–12 students participate in the 50‐min laboratory period that includes a 15‐min discussion of the basic principles that underlie NAA, followed by the irradiation and gamma‐ray counting of a sample containing ‘‘unknown’’ elements. Students carry away copies of data printouts for out‐of‐class analysis. The exercise has been implemented in an introductory, calculus‐based general physics course with approximately 200 students.