Use structured evaluation data and user feedback to produce a systematically improved Version 2 design — mastering the iteration cycle.
Learn — read and understand
What design iteration means — and why V1 is never final
Iteration is the cycle of building, testing, evaluating, and improving. Professional designers expect Version 1 to have problems — finding and fixing them IS the design process. At Grade 6, the iteration cycle is: Print V1 → evaluate against success criteria → collect user feedback → identify root causes → write ECRs → model V2 → print V2 → evaluate V2 vs V1. Each iteration must be documented — not just done.
Root cause analysis: finding the real source of a problem
Surface problems have root causes. 'The lid doesn't close' is a symptom. Root cause analysis uses the '5 Whys': Why doesn't the lid close? → The lid outer dimension is 2mm too large. Why? → The tolerance was not applied correctly. Why? → The mating face dimension was taken from the wrong reference point. Why? → The inner box was measured from its outer edge instead of its inner edge. Root cause: wrong measurement reference point. Fix: re-measure from the correct reference.
Types of feedback: quantitative, qualitative, and observational
Quantitative feedback uses numbers: 'measured hole at 6.8mm vs 7.5mm spec.' Qualitative feedback uses user words: 'the lid feels too tight.' Observational feedback records what users DO: 'user tried to remove lid 3 times before succeeding.' All three types are valid design data. Grade 6 evaluation must include at least one piece of each type. Observation is the most honest — users do not always accurately describe what they do.
Writing an ECR (Engineering Change Request) for V2
An ECR formally documents a design change. Format: (1) Issue — describe the problem with evidence. (2) Root cause — what caused it? (3) Change — exact dimension or design modification. (4) Expected outcome — what will this change produce? Example: Issue: lid too tight — measured 0.0mm clearance. Root cause: tolerance not applied. Change: increase lid outer dimensions by 0.4mm. Expected outcome: clearance fit achieved; lid slides on/off with one hand.
Explore — the V1 → V2 improvement cycle in practice
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V1: evaluate against criteria
Score each success criterion 1–4. Measure. Collect user feedback. Observe the user interacting with the object.
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Root cause analysis
For every criterion below 3/4: ask Why? 5 times. Do not write ECRs without first identifying the root cause.
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Write ECRs for V2
One ECR per issue. Issue, root cause, exact change, expected outcome. Maximum 3 ECRs per iteration cycle.
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V2 evaluation vs V1
After printing V2: re-evaluate the same criteria. Score must improve on the changed criteria. Document the improvement.
Activity — put the V1 → V2 iteration steps in the correct order
Drag or tap a label, then drop/tap on a zone
Evaluate V1 against criteria
Perform root cause analysis
Write ECRs for V2
Print and evaluate V2
Step 1
Step 2
Step 3
Step 4
Quiz — Design iteration, 5 questions
1Design iteration is BEST described as:
2Root cause analysis answers the question:
3Which type of feedback is considered the MOST honest at Grade 6 level?