Students are introduced to the concept of light pollution by investigating the nature, sources and levels of light in their classroom environment. They learn about the adverse effects of artificial light and the resulting consequences on humans, animals and plants: sky glow, direct glare, light trespass, animal disorientation and energy waste. Student teams build light meters using light sensors mounted to LEGO MINDSTORMS NXT intelligent bricks and then record and graph the light intensity emitted in various classroom lighting situations. They are introduced to the engineering concepts of sensors, lux or light meter, and lumen and lux (lx) illuminance units. Through this activity, students also learn how to better use light and save energy as well as some of the technologies designed by engineers to reduce light pollution and energy waste.