What is �creping� and how is it responsible for the softness of toilet paper? Why is it important to temper chocolate before you mold it? Why do D batteries last longer than AAA? And how do you � Off The Fence 2014 3 build one of the fastest road bikes in the world? Find out the answers to these questions and more in this episode of �Who Knew? With Marshall Brain.� Take a fast-paced and fact-filled adventure into the world of product design, manufacturing and testing as we go behind-the-scenes to find out how people and machines create some of life�s most fascinating things.