In a hands-on way, students explore light's properties of absorption, reflection, transmission and refraction through various experimental stations within the classroom. To understand absorption, reflection and transmission, they shine flashlights on a number of provided objects. To understand refraction, students create indoor rainbows. An understanding of the fundamental properties of light is essential to designing an invisible laser security system, the ongoing objective in this unit. This engineering curriculum meets Next Generation Science Standards (NGSS).