In this power-packed and widely-used chemistry activity for grades 6-10, an ordinary ziplock bag becomes a safe and spectacular laboratory. Students mix chemicals that bubble, change color, get hot, and produce gas, heat, and an odor. They then conduct experiments to determine what causes the heat in this chemical reaction. This exciting activity explores chemical change, as well as endothermic and exothermic reactions, and serves as an effective and inviting introduction to many aspects of chemistry.