Sal Khan has stated that his website Khan Academy was one of the first resources to use technology to personalize education, and that prior to the development of home computers and the internet, education was more or less static—claims that education journalist Watters takes issue with. She begins this powerful treatise by countering the mythology that computers jump-started 20th-century American educational innovations and reforms. Earlier in the 20th century, teaching machines were developed in fits and starts, decades prior to the advent of computers and the internet, and she offers a fascinating glimpse into the “science of teaching and learning” that emphasized machine-based content mastery through incremental learning. Devices such as the Teaching Machine, AutoTutor, Didak, Automatic Teacher, TEMAC, and Markograph were intended to free up a teacher’s time from mundane scoring tasks to devote individualized attention to students and allow time for “real teaching.” Later, instructional materials were designed for some of the machines, providing individualized instruction with prompt feedback mechanisms. Notably, programmed instruction was used as part of literacy efforts related to the civil rights movements and voting rights outreach. Watters stresses that a full understanding of teaching machines requires an examination of how “corporations dragged their feet, slowed the development of products, stalled the market, resisted the latest sciences, and, in many ways, balked at educational change.” VERDICT Historians of educational technology and education reform will relish this thoroughly researched and well-referenced work.