In the 1970s, environmentalists in the United States came up with the concept of human impact (I) on the environment, which was conceived of as a product of the population (P), affluence (A) and technology (T). This equation, the IPAT equation, provides insights and has limitations. This video explores these ideas. This video is based on the Sustainability Learning Suites created by Jane Qiong Zhang and Linda Vanasupa in association with Julie Zimmerman and Jim Mihelcic.