This guided inquiry, laboratory-based lesson has students measure the speed of light using marshmallows and a microwave. This experiment can easily (and safely) be given to students to do at home. The full lab guide contains background, purpose, materials, procedure and wrap-up questions. The powerpoint gives a short history of science lesson about the speed of light. Finally, although this part may not work on its own, I have left in the quiz that I usually give at this part of my optics unit. The rest of the unit is available for sale (or will be soon), so the quiz can give you a preview of what else I do in this unit.