The model; test; refine iterative cycle is a repeated design process in which a designer represents an idea, evaluates its performance, and modifies it using evidence. The cycle is repeated until the design meets its requirements as effectively as possible.
How the cycle works
| Stage | What the designer does | Purpose |
|---|---|---|
| Model | Produces a representation of the proposed solution, such as a sketch, physical prototype, computer-aided design model, simulation, or working model. | Makes the idea visible or testable before committing to final production. |
| Test | Evaluates the model against measurable design specifications, user requirements, and relevant constraints. Testing may collect quantitative data, qualitative user feedback, or both. | Identifies strengths, weaknesses, failures, and opportunities for improvement. |
| Refine | Changes the design in response to the test evidence. This may involve altering dimensions, materials, mechanisms, ergonomics, form, or manufacturing methods. | Improves how successfully the design satisfies the specification. |
After refinement, the changed design is modelled and tested again. Each repetition is called an iteration, and evidence from one iteration informs the next.
For example, a designer developing a reusable bottle might model a lid, test it for leakage and ease of opening, and discover that users cannot grip it securely. The designer could refine the lid by increasing its diameter and adding a textured surface, then produce and test a new model.
A common misconception is that refinement means making a product look better. Refinement can improve appearance, but it must respond to testing and may instead address function, safety, usability, sustainability, cost, or manufacturability.
Exam technique
For IB Design Technology subtopic B2.1 The design process, do not describe the stages as a one-way sequence. Explain that the process is iterative, identify how test evidence leads to a specific design change, and link evaluation to the design specifications. In an applied question, use the pattern: model produced, test conducted, evidence collected, refinement made, and cycle repeated.