Even exothermic reactions such as burning wood need energy to get started. What is that energy used for and where does it come from? This PowerPoint presentation examines the evidence that there is more to a reaction than bond breaking and bond making. It illustrates how effective collisions result in the formation of a high energy, transitory activated complex. If a picture is worth a thousand words, perhaps an animation is worth even more. The animation at the end of the presentation showing how water might form from hydrogen and oxygen takes the concept from the realm of hollow words to something concrete.