Functional Design and ADDIE/ISD

Functional design and ADDIE/ISD inform each other and are capable of working in a complementary way. Probably the two themes most important in describing the relationship are sequentiality and granularity.

Sequentiality refers to the issue of design decision order. Designs are large and complex enough—even the simplest ones—that they cannot be created in a single stroke. Designing is decision-making process, and therefore some decisions have to be made before others. ADDIE/ISD models specify a general order of data gathering and decision-making processes. Logically it does not make sense for some of these processes to come before others. At the same time, ADDIE/ISD models have been criticized for their tendency to promote “waterfall” thinking, which tends to be linear and which prevents the designer from anticipating the outlines of designs early-on: frustrating clients and designers alike.

Functional design orders design decisions according to project-specific patterns in response to constraints imposed by the problem’s context.  ADDIE/ISD models represent an idealized case in which it is seldom made clear how prior constraints impact the idealized model’s processes. Functional design assumes the existence of prior constraints for every design problem that force the designer to re-assess the order of decision-making. Design order in functional design is determined by the “next most critical” rule for selecting decisions to be made, assuming that certain decisions have been made or are strongly indicated even before the project is launched, creating the “seed” from which the design expands outward in increasing detail.

Granularity refers to the degree of guidance provided to designers by a design approach. Functional design and ADDIE/ISD probably differ to the greatest degree with respect to granularity. This is because functional design operates within the same context as ADDIE/ISD, overlapping to some extent some of the ADDIE/ISD processes. However, functional design deals with the concerns of design within this context at a much smaller granularity and therefore scaffolds design efforts to a much higher degree during the critical phase where the design itself is being formed.

Functional design also recognizes that design decisions begin during what is normally recognized as a design phase but that they also continue to be made throughout what is normally called the development phase. Functional design therefore considers all decisions, from the highest level down to the lowest, to be design decisions. What are normally considered production tasks are therefore treated as design tasks, and the existence of a development phase is de-emphasized.