This lesson plan discusses how geothermal power plants generate electrical energy from heat energy. The objectives are to explain the relationship between heat, work and efficiency, and how power plants generate and transmit electrical energy using heat transfer and energy transformation. The lesson will explain how heat energy from the Earth's core is transferred to electrical energy in geothermal power plants. Students will analyze a diagram of a geothermal power plant and explain the process of how heat energy is converted to mechanical then electrical energy.