Component Display Theory (CDT) is a theory of instruction consisting of three parts: (1) a scheme for describing the content to be taught—the task/content matrix; (2) a scheme for describing instructional strategies—primary presentation forms, secondary presentation forms, and interdisplay relationships; and (3) a set of rules that relate the two. CDT was created during the 1970s by M. David Merrill, director of the Brigham Young University (BYU) Division of Instructional Research, Development, and Evaluation. Merrill’s students at BYU conducted many research studies exploring aspects of the task/content matrix, primary presentation forms, secondary presentation forms, and interdisplay relationships. The results of these efforts were then formalized into CDT because each primary presentation form comprised or could comprise a display to a student. These displays are the ...