Apply human-centred design principles to create objects measured to a real user's needs — incorporating anthropometrics, ergonomics, and user testing.
Learn — read and understand
Human-centred design: the user is the specification
Human-centred design (HCD) places the real user at the centre of every design decision. The process: (1) Observe — watch how the user interacts with the current situation. (2) Define — write specific problem statements from the user's perspective. (3) Measure — take anthropometric measurements of the user's body and context. (4) Design — create a solution that fits those measurements. (5) Test — put the solution in front of the real user.
Anthropometrics: measuring the human body
Anthropometrics is the science of measuring human body dimensions. For product design: hand span (palm width across knuckles — average Grade 6 student: 75mm), grip diameter (diameter of a comfortable cylindrical grip — 25–35mm), index finger width (approximately 17mm for Grade 6). These measurements are not estimates — they must be measured from the actual user.
Ergonomics: designing for comfort and natural use
Ergonomics is designing objects to fit natural human movements and reduce strain. For a hand-held object: the grip diameter should match the hand's comfortable grip range (25–35mm). The object should not require wrist twisting to operate. Weight distribution should be towards the hand, not the tip. Edges must not dig into the palm. For a desk object: it should be reachable without leaning and usable without picking it up.
User testing protocol: how to test with a real person
User test protocol: (1) Brief the user in one sentence only — don't coach. (2) Give them the object and a task: 'Use this to hold your three most-used pens.' (3) Watch silently — observe fumbling, confusion, unused features. (4) Time the task. (5) After task: ask three questions — 'What worked?' 'What didn't?' 'What's missing?' Record answers verbatim. User test data drives design decisions.
Explore — anthropometric measurements for common objects
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Grip diameter
Comfortable cylindrical grip: 25–35mm diameter. Below 20mm feels like a pencil; above 40mm is a two-handed grip.
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Button / slot width
A button or slot meant for a single finger: minimum 17mm wide, 15mm tall. Anything smaller requires precision to activate.
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Hand-held device width
A device held in one hand should not exceed palm width: 70–80mm for Grade 6 students. Wider = requires two hands.
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Control reachability
Any button or feature that needs one-handed operation must be within 50mm of the grip point — typical thumb reach without shifting grip.
Activity — match each product requirement to the correct anthropometric measurement
Drag or tap a label, then drop/tap on a zone
25–35mm diameter
17mm minimum width
≤75mm wide
≤50mm from grip
One-handed grip comfort
Single-finger button
Single hand can wrap around it
Thumb reaches without regripping
Quiz — Human-centred design, 5 questions
1What does 'anthropometrics' mean?
2During a user test, why should you NOT coach the user?
3A comfortable grip diameter for a Grade 6 student's hand-held object is:
4Ergonomics is BEST described as:
5Why must anthropometric measurements come from the ACTUAL user, not average statistics?