ISD as a Design Science
While some learning theory is part of the descriptive sciences, which describe the way things function in the natural world; Instructional System Design is more a part of the design sciences, which offer ways to perform certain human-defined tasks. Descriptive sciences can be considered the law as they aim to describe and explain, while design sciences are roadmaps that guide our knowledge and skills for the activities of design (Grimaldi, Engel, 2007).
Being a design science, ISD is a model to aid in the design, development, and delivery of performance through learning, training and development processes. Since there is “science” in the term, it must be evidence based. However, because we are dealing with one of the most complex objects known to us — the human mind, at times there is not enough evidence. For this reason we have “design” in the term, which means there is also art.
Joel Michael writes in Advances in Physiology Education (2006):
“…it is important to recognize that educational research is difficult to do; this has been cogently highlighted by Berliner (8) in Educational research: the hardest science of them all. Berliner points out that unlike a physics experiment, in which it is possible to readily distinguish between the independent and dependent variables, and also possible to isolate and control all of the independent variables, in educational experiments all of this is problematic. Researchers may not agree on which variable is the dependent variable of greatest interest or importance. There may be disagreements about which independent variable(s) are to be manipulated. There may be disagreements about how to measure any of the relevant variables. And, finally, it may be extremely difficult, or even impossible, to isolate and manipulate all the variables suspected of being involved in the phenomena being studied.”
This means the people within the organization, to include learners, designers, & managers must control the ISD model, rather that it controlling them. Immediate problems often arise that require rapid solutions. Don't get hung up in the system model by refusing to bypass steps, switch steps, modify steps, or including steps of your own. Managers often need quick and ingenious solutions, not another bureaucracy. In other words, the learning department's motto should be: “We provide learning and performance solutions!” Not, ”We follow the ISD model.”
Thus, the steps in each phase should not be thought of as concrete in nature but rather dynamic and iterative (Merrienboer, 1997). One phase or step does not necessarily have to be completed before the next one is started, hence the dashed-arrows in the diagram below that show the processes or phases can be iterated: