In this science lesson, the teacher discusses different types of switches and their functions, using examples such as a torch to illustrate their application in circuits. The lesson covers the basic components needed for a circuit, including a battery, light bulb, and switch, and demonstrates how a push button switch operates by completing and interrupting the circuit. Additionally, the teacher explains other types of switches like toggle and slide switches, noting their use in various everyday applications like old Maltese buses and airplanes.