Centuries ago, the Inca developed ingenuous suits of armor that could protect warriors from even the fiercest physical attacks. These hardy structures were made not from iron or steel, but rather something unexpectedly soft: cotton. Today cotton is used to make everything from fabric, to currency, diapers and fishing nets. Michael R. Stiff explores the science of what makes cotton so versatile. Lesson by Michael R. Stiff, directed by WOW-HOW Studio.