This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. A Basic Topics section discusses atomic structure, emphasizing states of matter at high temperature and spectroscopic analysis of light from the stars. A section on Intermediate and Advanced Topics provides greater detail and more mathematical analysis of spectroscopy theory, including the quantum theory of electromagnetic radiation, electron orbits, and the classification of stellar spectra. Appendices include a glossary of unfamiliar terms, references and teaching aids, suggested class exercises, and questions and answers. (MH)