Chapter 11: Design, Prototyping and Construction

Chapter Introduction | Web Resources | Assignment Comments | Teaching Materials


The main aims of this chapter are to:

  • Describe prototyping and different types of prototyping activities.
  • Enable you to produce simple prototypes from the models developed during the requirements activity.
  • Enable you to produce a conceptual model for a product and justify your choices.
  • Explain the use of scenarios and prototypes in design.
  • Discuss a range of support available for interaction design.


Design activities begin once some requirements have been established. The design emerges iteratively, through repeated design-evaluation-redesign cycles involving users. Broadly speaking, there are two types of design: conceptual and physical. The former is concerned with developing a conceptual model that captures what the product will do and how it will behave, while the latter is concerned with details of the design such as screen and menu structures, icons, and graphics. We discussed physical design issues relating to different types of interface in Chapter 6 and so we do not return to this in detail here, but refer back to Chapter 6 as appropriate.

For users to evaluate the design of an interactive product effectively, designers must prototype their ideas. In the early stages of development, these prototypes may be made of paper and cardboard, while as design progresses and ideas become more detailed, they may be polished pieces of software, metal, or plastic that resemble the final product.

There are two distinct circumstances for design: one where you're starting from scratch and one where you're modifying an existing product. A lot of design comes from the latter, and it may be tempting to think that additional features can be added, or existing ones tweaked, without extensive investigation, prototyping, or evaluation. It is true that if changes are not significant then the prototyping and evaluation activities can be reduced, but they are still invaluable activities that should not be skipped.

In Chapter 10, we discussed some ways to identify user needs and establish requirements. In this chapter, we look at the activities involved in progressing a set of requirements through the cycles of prototyping to construction. We begin by explaining the role and techniques of prototyping and then explain how prototypes may be used in the design process. Design support plays an important part in development, but it changes so rapidly that we do not provide a catalog of current support but instead discuss some examples currently available.