The flashlight is a simple device that is composed of a lightbulb, usually two cells connected in series, a housing, a switch, and a reflector for the light. All flashlights essentially use these parts to complete a circuit that converts the stored chemical energy in the cells to light energy. In this lesson, students will take apart an inexpensive flashlight to determine how the parts work together to produce light. Students will then make a flashlight of their own design using common household materials. Like all lessons in the Everyday Engineering series, this one follows the 5E learning cycle model.