Having worked thirty-five years as a process engineer and manager in the chemical industry, Henry Pfeffer decided to retire in 2009 to pursue a second career as a high school science teacher. While preparing for the teacher certification exams, he reviewed current college textbooks in physics, biology, astronomy, and earth science, and he was surprised to discover how much our knowledge in each of these scientific fields had progressed over the last forty years. As an engineer, he solved "real-life" problems by learning how to piece together bits of data to create mental models of chemical...