2025 CCEA AS-Level Technology and Design 8900 Practice Paper with Answers

Aluminium alloy has a low density compared with other structural metals such as steel, meaning a frame of a given size and strength is significantly lighter, which is important for a bench that must be regularly folded and carried. It also has good corrosion resistance: when exposed to air, aluminium naturally forms a thin, tough aluminium oxide layer on its surface that protects the metal underneath from further oxidation, so the bench can be left outdoors in wet weather without rusting in the way an untreated steel frame would. Answer: low density/lightweight, and good corrosion resistance.

2 marks for each correctly stated property, to a maximum of 4 marks: [1] for naming a valid property, [1] for linking it to why it suits this application (lightweight -> portability/folding; corrosion resistance -> outdoor/damp use). Accept other valid properties: good strength-to-weight ratio; can be extruded into complex frame sections. Reject unqualified 'strong' or 'durable' with no link to the application.

Hardwoods are obtained from broad-leaved, deciduous trees (angiosperms), which typically lose their leaves in winter and tend to grow more slowly, often producing a denser timber; a named example is oak. Softwoods are obtained from coniferous, evergreen trees (gymnosperms), which typically keep their needle-like leaves year-round and grow faster; a named example is pine. It is important to note the terms 'hardwood' and 'softwood' refer to the botanical classification of the tree, not a direct measure of the timber's physical hardness — for example, balsa is technically a hardwood despite being very soft. Answer: hardwoods (e.g. oak) come from broad-leaved, deciduous trees; softwoods (e.g. pine) come from coniferous, evergreen trees.

[1] correct definition of hardwood (broad-leaved/deciduous tree); [1] valid named hardwood example (e.g. oak, beech, ash, mahogany); [1] correct definition of softwood (coniferous/evergreen tree); [1] valid named softwood example (e.g. pine, spruce, larch, fir). Full marks require both definitions AND both named examples; a definition alone without a valid named example loses that example mark.

HDPE has good impact resistance and toughness, meaning a watering can made from it can be dropped, knocked or stepped on in a garden setting without cracking or shattering, unlike a more brittle material. It also has excellent resistance to moisture and many chemicals, so it will not rot (like an untreated wood might), rust or corrode (like an untreated metal might) from repeated contact with water, fertiliser or plant feed, making it durable for long-term outdoor use. It is also lightweight and can be injection- or blow-moulded into complex hollow shapes, though the two properties most directly suited to this specific application are impact resistance and moisture/chemical resistance. Answer: good impact resistance/toughness, and good resistance to moisture and chemicals.

2 marks for each correctly stated property, to a maximum of 4 marks: [1] for naming a valid property, [1] for linking it to why it suits a watering can (impact resistance -> being dropped/knocked in a garden; moisture/chemical resistance -> repeated contact with water/plant feed without rotting or corroding). Accept other valid properties: lightweight; can be moulded into a complex hollow shape (e.g. via blow moulding). Reject unqualified 'waterproof' with no development.

Stage 1 (Hopper): plastic granules (e.g. HDPE or polypropylene) are loaded into a hopper at the top of the machine, which feeds them by gravity into the heated barrel. Stage 2 (Heated barrel and screw): inside the barrel, a rotating Archimedes screw carries the granules forward while heater bands around the barrel melt them into a viscous liquid; the rotating screw also mixes the melt to an even temperature and builds up pressure ahead of it. Stage 3 (Injection through the nozzle): once enough molten plastic has built up, the screw is driven forward like a ram, forcing (injecting) the molten plastic at high pressure through a nozzle and into the sprue and runners of a closed, two-part steel mould shaped as the negative of the plant pot tray. Stage 4 (Cooling): the mould, which is water-cooled, holds the plastic under pressure while it cools and solidifies into the shape of the tray; cooling channels within the mould remove heat quickly so the cycle time is kept short, which matters for producing a large batch of 5,000 trays efficiently. Stage 5 (Ejection): once solid, the two halves of the mould open, and ejector pins push the finished tray out of the mould, which then closes again ready to repeat the cycle. Answer: the labelled stages are hopper feed, heating/melting via the rotating screw in the barrel, injection of molten plastic into the closed mould via the nozzle, cooling of the plastic within the mould, and ejection of the finished tray by ejector pins as the mould opens.

1 mark for each correctly described and appropriately labelled stage, to a maximum of 5 marks: [1] hopper feeding granules into the barrel; [1] heating/melting of the granules via heater bands and the rotating screw; [1] injection of molten plastic through the nozzle into the closed mould under pressure; [1] cooling/solidifying of the plastic within the (typically water-cooled) mould; [1] mould opening and ejector pins ejecting the finished part. Credit is for describing the function of each stage as if labelling a sketch, not for a literal drawing.

Computer Integrated Manufacture (CIM) refers to the use of computer systems to link together and control every stage of the manufacturing process — including product design (CAD), production planning, CNC/CAM manufacture, stock control, and quality monitoring — so that information generated at one stage (for example, a bench leg's dimensions in a CAD model) is automatically shared with and used by the next stage (for example, generating the CNC toolpath to cut that leg, and updating stock records for the timber used), without needing to be manually re-entered. One advantage in a furniture factory producing garden benches is that it increases production speed and consistency while reducing human error: because data flows automatically between design, manufacture and stock systems, a design change (e.g. a different leg length) can be updated once in the CAD file and will automatically be reflected in the CNC cutting instructions, reducing the risk of a worker manually transcribing the wrong measurement and producing incorrectly sized parts. Answer: CIM is the use of computers to link and automatically share data across the whole manufacturing process, from design to production to stock control; a key advantage is faster, more consistent production with reduced risk of human error from manual data re-entry.

[1-2] for the definition — [1] basic idea that computers are used to control manufacturing; [2] full definition referencing the linking/integration of multiple stages (e.g. design, production, stock control) with automatic data sharing. [1-2] for the advantage — [1] a valid but undeveloped advantage (e.g. 'it is faster'); [2] a valid advantage explained specifically in the context of the furniture factory (e.g. reduced risk of transcription error when a design change is applied). Accept other valid advantages: reduced waste through more accurate stock/material ordering; greater flexibility to produce different bench designs without significant retooling time.

Ergonomic factors: the handles of a pruning shear must be sized and shaped to comfortably fit a wide range of hand sizes (typically designed around anthropometric data spanning the 5th to 95th percentile of adult hand span), so that both a small-handed and a large-handed user can achieve a secure, comfortable grip without straining their fingers; a soft, textured, rubberised over-moulding on the handle improves grip and comfort compared with bare, hard plastic, reducing the chance of the tool slipping in a wet or gloved hand; the pivot point and blade geometry are designed to give good mechanical advantage (leverage), so that a relatively small hand force applied at the handles is multiplied into a much larger cutting force at the blade tip, reducing user fatigue and strain when pruning repeatedly over a session; a spring-loaded return mechanism automatically reopens the blades after each cut, reducing the repetitive muscular effort the user's hand must make. Safety factors: a rotating safety lock or catch is fitted so the blades can be locked shut when not in use, preventing accidental opening and injury during storage or transport; a finger guard or bumper positioned near the pivot prevents the user's fingers from being caught between the handles as the blades close; the cutting blade is typically a bright, contrasting colour (e.g. orange) so it remains visible against soil or foliage if set down, reducing the risk of an accidental cut from misplacing the tool; the handle material and shape are also chosen to minimise slipping, since a hand sliding forward onto a closing blade would be a serious safety hazard. A well-integrated design, such as a locking mechanism built into the same textured handle grip used for comfort, shows how ergonomic and safety considerations often reinforce one another rather than being addressed separately. Answer: ergonomic factors include handle sizing/shape for a range of hand sizes, grip material, and leverage to reduce cutting force; safety factors include a locking mechanism, finger guards, and high-visibility, non-slip materials — illustrated throughout by specific pruning shear features.

3-tier Levels-of-Response. Level 1 (1-3 marks): basic, undeveloped points on ergonomics or safety (not both), minimal linkage to the pruning shear example, limited specialist vocabulary. Level 2 (4-6 marks): good explanation covering both ergonomic AND safety factors with clear, if not fully developed, linkage to the pruning shear context; adequate structure and terminology. Level 3 (7-9 marks): comprehensive, well-organised discussion covering multiple ergonomic factors (e.g. anthropometric handle sizing, grip material, mechanical advantage) AND multiple safety factors (e.g. locking mechanism, finger guard, high-visibility colour), each illustrated with a specific, accurate example; fluent use of technical vocabulary and clear structure.

(a) Four valid specification points: (1) the pot must stack neatly inside similar pots for compact storage and display in the garden centre; (2) the pot must include drainage holes in the base to prevent waterlogging and root rot; (3) the pot must be weather-resistant (UV-stable and non-absorbent) so it does not degrade, fade or crack when left outdoors; (4) the pot must be lightweight enough for a customer to comfortably lift and carry once filled with compost and a plant. (b) Example design description: the pot is a tapered, round pot, 200 mm in diameter at the rim and 180 mm tall, with the diameter reducing to approximately 160 mm at the base — this taper (a draft angle of a few degrees) allows one pot to nest inside another for compact stacking, directly meeting specification point (1). The pot is manufactured from UV-stabilised polypropylene, chosen because it resists becoming brittle or fading under prolonged sunlight and does not absorb water, directly meeting specification point (3) on weather resistance; polypropylene is also relatively lightweight compared with fired clay, helping meet specification point (4). The base includes four 8 mm diameter drainage holes arranged in a cross pattern, meeting specification point (2) by allowing excess water to escape and preventing the compost from becoming waterlogged. A moulded lip around the rim, approximately 15 mm wide, adds rigidity to the pot wall (so the plastic does not flex or crack when lifted while full) and provides a comfortable, rounded edge for a customer's hand to grip when carrying it. Answer: any four valid, relevant specification points, and a design description with realistic dimensions, a named suitable material, and a clear, explicit explanation of how at least three named features address three of the stated specification points.

(a) [4]: 1 mark per valid, relevant specification point, to a maximum of 4 (accept: stackability, drainage, weather/UV resistance, lightness/portability, cost, aesthetic appeal/colour range, durability against impact). (b) [6], 3-tier Level-of-Response: Level 1 (1-2 marks) — basic description with vague or missing dimensions/material, addresses specification points only superficially or not at all. Level 2 (3-4 marks) — reasonably detailed description with some realistic dimensions and a named material, addressing at least two specification points with some explanation. Level 3 (5-6 marks) — detailed, realistic description with specific dimensions and a clearly justified material choice, explicitly and convincingly explaining how named design features meet at least three specification points from part (a).

(a) An open-loop control system produces an output based only on a pre-set input, with no feedback to check whether that output has achieved the desired result — for example, if the greenhouse fan were simply switched on by a timer for 10 minutes every hour regardless of the actual temperature, the system has no way of knowing whether the greenhouse has actually cooled down. A closed-loop control system, by contrast, uses feedback: a sensor (here, the thermistor) continuously measures the actual temperature and feeds this information back to the controller, which adjusts the output (switching the fan on or off) accordingly, so the system responds to the real, current state of the greenhouse rather than following a fixed, unresponsive schedule. (b) R1 is a fixed resistor that, together with R2, forms a potential (voltage) divider: it limits the current drawn from the supply and sets the range over which the junction voltage can vary as R2 changes. An NTC (negative temperature coefficient) thermistor is used for R2 because its resistance decreases as temperature increases (the defining property of an NTC device) — this means a rise in greenhouse temperature directly and predictably lowers R2's resistance, which changes the voltage divider's output voltage in a way the comparator circuit can detect and use to trigger the fan; a fixed resistor could not do this because its resistance does not respond to temperature at all. (c)(i) Vout = Vin × R2 / (R1 + R2) = 12 × 2200 / (4700 + 2200) = 12 × 2200 / 6900 = 26400 / 6900 = 3.826... ≈ 3.83 V. (ii) The series resistor must drop the difference between the supply voltage and the LED's forward voltage, at the required current: R = (Vs − Vf) / I = (9 − 2) / 0.02 = 7 / 0.02 = 350 Ω. (iii) T = 1.1 × C × R = 1.1 × (100 × 10⁻⁶) × 47000 = 1.1 × 4.7 = 5.17 s. Answer: (c)(i) Vout = 3.83 V; (c)(ii) R = 350 Ω; (c)(iii) T = 5.17 s.

(a) [4]: [1-2] open-loop correctly explained (output with no feedback, e.g. a fixed-time fan); [1-2] closed-loop correctly explained (feedback from a sensor continuously adjusts the output); both must reference the greenhouse fan example for full marks. (b) [4]: [1-2] R1's function correctly explained (limits current / sets up the voltage divider with R2); [1-2] NTC thermistor correctly explained (resistance falls as temperature rises, allowing temperature to be sensed as a changing voltage); full marks require reference to why a fixed resistor could not do this job. (c) each sub-part [4], own-figure rule (ECF) applies throughout: (i) [1] correct formula quoted, [1] correct substitution (12 × 2200/(4700+2200)), [1] correct working, [1] final answer 3.83 V (accept 3.8 V to 3.83 V) with unit V. (ii) [1] correct formula (R = (Vs−Vf)/I), [1] correct substitution, [1] correct working, [1] final answer 350 Ω with unit. (iii) [1] correct formula quoted, [1] correct substitution, [1] correct working, [1] final answer 5.17 s (accept 5.2 s) with unit s. No marks for a bare correct answer with no working shown.

(a) The fan must switch on (F=1) only when BOTH T=1 and D=1; in every other combination it must stay off (F=0). Completed table: T=0,D=0 -> F=0; T=0,D=1 -> F=0; T=1,D=0 -> F=0; T=1,D=1 -> F=1. (b) This truth table (output is 1 only when both inputs are 1) is the definition of the AND function, so the required gate is an AND gate, with Boolean expression F = T · D (equivalently written F = T AND D). (c) A single npn transistor has a current gain (hFE) typically in the range of perhaps 50-300, meaning the maximum collector current it can switch is hFE multiplied by the (small) base current the logic gate can supply — for a very small logic-level base current, this may still not be enough to fully switch on (saturate) a transistor driving a real motor's operating current. A Darlington pair consists of two transistors connected so that the emitter current of the first transistor becomes the base current of the second; its overall current gain is approximately the product of the two individual gains (hFE(total) ≈ hFE1 × hFE2), which can be several thousand. This means a very small logic-level base current into the first transistor can control a much larger collector current through the second transistor, making it far better suited to switching a motor's higher operating current from a low-current logic gate output than a single transistor would be. (d) Design description: the AND gate's output (5 V logic level, low current) connects through a base resistor (e.g. approximately 1 kΩ, its value chosen to limit the base current of the transistor to a safe level while still ensuring the transistor is driven into saturation) to the base of an npn transistor (or, given the current requirement discussed in part (c), the base of a Darlington pair). The transistor's emitter is connected to 0 V (common ground with the logic circuit), and its collector is connected to one terminal of the 12 V fan motor, with the motor's other terminal connected to the separate +12 V supply rail — this arrangement allows the low-voltage, low-current logic signal to switch the higher-voltage, higher-current motor circuit safely, since the transistor's collector-emitter path, not the logic gate, carries the motor current. A protection (flyback) diode is connected directly across the motor terminals, with its cathode toward the +12 V rail, so that it is reverse-biased and does not conduct during normal operation; when the transistor switches off and the motor's current suddenly stops, the diode provides a safe path for the back-EMF voltage spike generated by the motor's inductive coil, protecting the transistor from being damaged by this voltage spike. Answer: (a) F = 0,0,0,1; (b) AND gate, F = T·D; (c) a Darlington pair's much higher combined current gain (hFE1 x hFE2) lets a small logic current switch the motor's larger current; (d) base resistor limits base current into the transistor, the transistor's collector-emitter path switches the 12V motor circuit, and a flyback diode across the motor protects the transistor from back-EMF.

(a) [4]: 1 mark per correct output row, to a maximum of 4. (b) [3]: [1] AND gate correctly named; [2] correct Boolean expression F = T·D (or F = T AND D; accept F = TD). (c) [4]: [1-2] correct explanation that hFE is the current gain, and a single transistor's available current may be insufficient for the motor; [1-2] correct explanation that a Darlington pair's gain is approximately the product of its two transistors' gains (hFE1 x hFE2), giving much greater amplification suited to driving the motor from a small logic current. (d) [9], 3-tier Level-of-Response: Level 1 (1-3 marks) — basic circuit idea (e.g. 'a transistor switches the motor') with components missing or unexplained, minimal technical vocabulary. Level 2 (4-6 marks) — most required components present (base resistor, transistor, protection diode) with a reasonable explanation of function, though possibly with an omission or minor inaccuracy (e.g. diode orientation not stated). Level 3 (7-9 marks) — all required components present and correctly explained: base resistor (limiting/setting base current), transistor correctly connected to switch the motor's higher-current circuit, and a flyback/protection diode correctly placed across the motor in reverse bias to protect the transistor from back-EMF; clear, fluent, well-organised technical description throughout.