Instructional Transaction Theory: An Instructional Design Model Based on Knowledge Objects: M. David Merrill

Instructional systems development (ISD) is a set of procedures for systematically designing and developing instructional materials. It has been described in a number of sources (e.g., Dick & Carey, 1990; Gagne, Briggs, & Wager, 1988). ISD is a set of procedural steps. The emphasis is primarily on what to do, rather than on how to do it, or why it works. ISD has many varieties but all involve five basic phases: analysis, design, development, implementation, and evaluation. ISD is not instructional design theory.