Design and Applied Technology: Process, Specifications and Justification
Design and Applied Technology (DAT) is the Category A senior secondary elective in which the HKDSE tests how candidates apply design thinking and technological principles to real products and systems. Questions typically reward a traceable design process, measurable specifications, justified material and process choices, and evaluation against evidence-not attractive sketching alone.
The design process must leave evidence
Treat design as an iterative loop: identify a genuine need; write a brief stating user, purpose and constraints; convert it into a product design specification (PDS); generate concepts; develop and prototype; test; evaluate; refine. In answers, name the stage and the decision made. A concept sketch without annotation earns little; an annotated sketch showing function, user interaction, dimensions and a rejected alternative earns more.
Write specifications you can test
A PDS turns vague wishes into criteria. Use numbers and methods: function, performance, ergonomics and anthropometrics (state the percentile, e.g. 5th–95th), safety, materials, manufacturing, cost, sustainability and standards. Each criterion should have a target and a test. 'Lightweight' is not a specification; 'mass ≤ 450 g' is.
Match material, process and end-of-life
Select materials by the properties required (strength-to-weight, toughness, thermal behaviour, electrical insulation), then by process constraints (injection moulding needs draft angles; sheet metal needs bend radii), then by joining, finishing and disposal. Use design for manufacture and assembly (DFM/DFA) and life-cycle assessment (LCA) to justify trade-offs, not as slogans.
Worked example: compact desk lamp
Need: students in small flats need adjustable task lighting without clamping damage. Brief: low-cost, portable, USB-powered. PDS targets: footprint ≤ 150 × 150 mm; illuminance ≥ 300 lux at 400 mm; head tilt 30–60°; mass ≤ 450 g; cost ≤ HK$120; external surface ≤ 45 °C; recyclable ABS body and aluminium arm; no sharp edges. Concepts are scored in a weighted matrix against the PDS (stability 30%, adjustability 25%, cost 20%, manufacturability 15%, sustainability 10%). Choose a weighted base plus friction hinge. Test with a lux meter at 400 mm, a tip-stability test and a thermal check after one hour. Evaluate against targets and state one refinement.
Traps that cost marks
Vague adjectives instead of a measurable PDS; ignoring the user or context; choosing materials without linking them to process; no test or evaluation; unsafe mains-voltage detail; confusing invention with innovation; ignoring intellectual property or sustainability; listing stages without decisions.