A 300-level modern physics class typically covers fundamental concepts in quantum mechanics, special relativity, nuclear physics, and astrophysics. Core topics often include the particle nature of light, matter waves, the time-independent Schrödinger equation, and quantum tunneling. The specific curriculum can vary significantly between institutions, influenced by the availability of related courses and the textbooks used, such as Tipler's Modern Physics and Serway/Moses/Moyer. Overall, the course aims to deepen understanding of modern physics principles beyond introductory levels.