Educational technology is the study and practice of using technology to improve learning and performance. It relies on a broad definition of technology that includes not just machines but also systems, methods, and techniques. The technology of education can be defined as tools that advance student learning and influence behavior. The field of technology education teaches students about technological processes and principles. The history of educational technology began with early tools like cave paintings but is often traced to educational films in the 1900s and mechanical teaching machines in the 1920s. There has long been a belief that new technologies could solve all learning problems, though predictions of books becoming obsolete, for example, did not come true.