This lecture discusses the Foucault pendulum, starting with a theoretical model and then demonstrating how to build one in a physics auditorium. The instructor explains the concept behind the pendulum's rotation and the technical challenges involved in maintaining its oscillation plane. The lecture also covers the experimental setup, including using electromechanical devices to release the pendulum and visual aids to observe its oscillation. By analyzing the pendulum's deviation over time, the instructor illustrates the impact of Earth's rotation on the pendulum's behavior, providing a practical example of theoretical concepts discussed in the course.