The “perpes” virus lab is a very fun lab to introduce forensic science students to the concept of Locard’s Principle (every contact leaves a trace). In addition, it can be used in biology classes during reproduction and chemistry classes when discussing acids, bases and indicators. First page is instructions with a list of chemicals and materials needed. Second and third page is students answer sheet. Note: Since this activity deals with adult subject matter, students are recommended to be at least in high school.