The spiral model was originaly conceved as a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts. The spiral model was defined by Barry Boehm in his 1988 article A Spiral Model of Software Development and Enhancement. This model was not the first model to discuss iterative development, but it was the first model to explain why the iteration matters. Design and development efforts are applied at each phase of the project, with an eye toward the end goal of the project. Kathy Cenammo and Deby Kalk adapt this model for instructional design in their book Real World Instructional Design. This model of development combines the features of the prototyping model and the ADDIE model.
The Spiral Model
The original spiral model, also known as the spiral lifecycle model, is comprised of 10 iterative steps which move software development to a higher and higher fidelity until it is completed. For the purposes of applying this model to instructional design, Cenammo and Kalk simplify the process into 5 steps:
- Define
- Design
- Demonstrate
- Develop
- Deliver
Advantages
- Estimates (i.e. budget, schedule, etc.) become more realistic as work progresses, because important issues are discovered earlier.
- The model is designed to cope with the inevitable changes to the learning experience that will happen over the course of design and delivery.
- Multimedia producers can get their hands in and start working on a project earlier, and therefore shape the design process as well.