Students are introduced to the (hypothetical) task of developing an invisible (non-intrusive) security system to protect the school's treasured mummified troll! Solving the challenge depends on an understanding of the properties of light. After being introduced to the challenge question, students generate ideas and consider the knowledge required find solutions. They watch a portion of the "Mythbuster's Crimes and Myth-Demeanors" episode ($20), which helps direct their research and learning toward solving the challenge. They begin to study laser applications in security systems, coming to realize the role of lasers in today's society.