A company wants to design a portable, adjustable laptop stand for students. The stand must:

• Be lightweight and foldable for carrying in a backpack
• Adjust to at least 3 different heights/angles
• Be stable on a desk when in use
• Suit laptops from 11" to 16"
• Be made from sustainable materials where possible

Using notes and sketches, design a laptop stand that meets these criteria. [20 marks: creativity 6, technical detail 6, communication 4, meeting brief 4]

→ The next best alternative forgone when an economic choice is made. (1 mark: "next best alternative", 1 mark: "forgone/given up")

→ 1. An increase in raw material costs (e.g. timber prices rising) raises production costs, reducing profitability at each price level, so firms supply less — supply shifts left. (2 marks: cause + mechanism + direction)
→ 2. The government introducing a new tax on the product increases costs, shifting the supply curve left as firms reduce output at each price. (2 marks)

For: Positive externality — reduced car use → less congestion and pollution (MSC of car travel > MPC). Subsidy lowers fares → more people use public transport → moves toward social optimum. Also: improved mobility for low-income groups (equity), reduced journey times for remaining drivers (less congestion).
Against: Opportunity cost — subsidy money could fund healthcare or education. May be inefficient if demand for public transport is price-inelastic (fares fall but ridership barely rises → large cost for small benefit). Subsidy may encourage unnecessary journeys. Risk of producer inefficiency if state-owned operators know they'll be subsidised regardless.
Judgement: Effectiveness depends on PED. If demand is elastic, small subsidy → large ridership increase → good value. A targeted subsidy (e.g. for off-peak travel, or for low-income groups) may be more efficient than a blanket subsidy. Singapore and London use a mix of subsidies + congestion charging — this dual approach may be more effective than subsidy alone.

Yes: Comparative advantage → countries produce what they're relatively best at → world output maximised → gains from trade. Consumers benefit from lower prices and more choice. Firms benefit from economies of scale (larger market). Competition from imports reduces domestic monopoly power. Example: Bangladesh specialises in textiles, Germany in high-end manufacturing — both benefit.
No: Over-specialisation risk — if demand for your export collapses, whole economy suffers (e.g. oil-dependent economies when oil prices crash). Infant industries in developing countries can't compete with established foreign firms without temporary protection. Strategic industries (defence, food security) may be too risky to rely on imports for. Dumping — foreign firms selling below cost to kill domestic competition. Free trade may exploit workers in countries with weak labour laws.
Judgement: Most economists support free trade with limited, targeted exceptions. The key is managed trade liberalisation — gradual, with support for displaced workers and protection for genuinely strategic sectors. The WTO framework aims to make this work, though it has flaws. The evidence strongly suggests that trade raises overall welfare, but the distribution of benefits matters — governments should use tax/transfer systems to compensate losers from trade.

1. Tariff imposed (Topic 6: International Trade)
→ 2. Price of imported steel rises (Topic 2: S+D — supply of imported steel shifts left)
→ 3. Domestic steel producers increase output — but steel-using industries (cars, construction) face higher costs (Topic 2: cost-push)
→ 4. Car prices rise → less affordable → lower quantity demanded (Topic 2: equilibrium shift)
→ 5. Car manufacturing employment may fall (Topic 3: labour demand is derived from product demand)
→ 6. Higher car prices contribute to inflation (Topic 4: cost-push inflation)
→ 7. Central bank may raise interest rates to control inflation (Topic 4: monetary policy)
→ 8. Higher rates → currency appreciation → exports harder, imports cheaper → trade balance worsens (Topic 6: exchange rates)
→ 9. Trading partners retaliate with their own tariffs (Topic 6: trade war)

Paper 2 gold: If you spot a chain like this in a data-response question and can explain 3+ links with correct terminology, you're hitting the top mark band.

Oil price ↑ → cost of production ↑ for transport, plastics, energy → SRAS shifts left → cost-push inflation → central bank raises interest rates → investment ↓, consumption ↓ → AD shifts left → lower growth, possible recession → imports ↓ (less consumer spending on foreign goods) → current account improves (but for bad reason) → currency may depreciate (lower interest rates expectations) → exports more competitive. Topics touched: 2, 3, 4, 6.

G ↑ → AD shifts right → short-run growth → but also: education improves human capital → LRAS shifts right → long-run productive capacity ↑ → potential growth ↑ → higher incomes → tax revenue ↑ → budget deficit may fall → also: more educated workforce attracts FDI → balance of payments may improve → but: opportunity cost (less spending on health/defence) → time lag (15+ years to see full returns). Topics touched: 2, 4, 5, 6.

Price Level ▲     LRAS (vertical at full capacity)
       │          |  SRAS (upward sloping)
       │         /|  AD = C+I+G+(X-M)
       │        / |  Equilibrium: AD = SRAS
       │       /  |  
    PL │──────●───|──  Shifts AD→ : P↑, Y↑ (growth)
       │     /|   |    Shifts AD← : P↓, Y↓ (recession)
       │    / |   |    SRAS← : P↑, Y↓ (stagflation!)
       │   /  |   |  
       │  /   |   |  AD
       │ /    |   |
       └──────────────► Real GDP (Y)
      Yfe = full employment output

Price Level ▲  LRAS1  LRAS2    Growth without inflation!
       │        |       |       More output at lower prices.
       │        |\      |       Caused by: better education,
       │        | \     |       infrastructure, technology,
       │        |  \    |       productivity, more resources.
    P1 │────────●──\───●─────    
       │        |   \  |\      
    P2 │────────|────\─●─\────   
       │        |     \|  \    
       │        |      |   AD  
       └──────────────────────► Y
          Y1 →  Y2

Inflation ▲                SRPC = short-run trade-off
      ▲    |                LRPC = vertical at NAIRU
      |    |SRPC            (natural rate of unemployment)
      |  ●A (low U, high π)  
      |    \               A→B: expansionary policy →
      |     \               lower U, higher π (short run)
      |      ●B             B→C: in long run, expectations
      |       \              adjust, U returns to NAIRU
      |        ●C            but π stays higher
      └────────|─────────►   Policy can't permanently
          NAIRU  Unemployment  reduce U below natural rate

Teacher said: "Create a table classifying 10 common materials. For each one, list the category, two key properties, and one real product that uses it. Explain why that material was chosen."

Teacher said: "Draw your finger-jointed box in isometric projection. Annotate the drawing with: dimensions, material, joint type, finish. Explain one design decision."

        ┌─────────────────────┐
       /│                     /│
      / │                    / │  ← Top: open (shows interior)
     /  │                   /  │
    ┌─────────────────────┐   │
    │   │                 │   │  150mm (length)
    │   │    INTERIOR      │   │
    │   │    (storage      │   │
    │   │     space)       │   │
    │   │                 │   │
    │   └─────────────────┼───┘
    │  /                  │  /   100mm (width)
    │ /    FINGER JOINT    │ /    ← Joint detail: 10mm fingers
    │/     (4 corners)     │/     at 10mm spacing, glued
    └─────────────────────┘      with PVA for strength
              80mm (height)

Material: 12mm pine (softwood) — chosen because it is easy to cut accurate finger joints in, lightweight for carrying, and inexpensive for a first project. Finish: Two coats of Danish oil — penetrates the wood to protect from moisture while keeping the natural grain visible. Design decision: I chose 10mm finger spacing (rather than 15mm) to give 5 fingers per joint instead of 3 — more glue surface area = stronger joint. The trade-off is more cutting time, but for a small box the extra strength is worth it.

Teacher said: "Write one paragraph comparing injection moulding and 3D printing. Cover: scale of production, cost, suitable materials, surface finish. Conclude with when you would use each."

Student answer (top marks):

Injection moulding and 3D printing (FDM) are both used to produce plastic parts, but they suit completely different production scenarios. Injection moulding is a mass production process — the steel mould costs £10,000–£100,000 to make, but once made, each part costs pennies and takes 15–60 seconds to produce. This makes it economical only for large quantities (100,000+ units). 3D printing has effectively zero tooling cost — you just send the digital file to the printer — but each part is relatively expensive and slow (hours per part), making it best for one-off prototypes or very small batches.

Injection moulding can use any thermoplastic (ABS, polypropylene, nylon) and produces parts with excellent surface finish and tight tolerances (±0.1mm). 3D printing is limited to specific filament materials (PLA, ABS, PETG) and leaves visible layer lines (typically 0.1–0.3mm per layer), so surface finish is rougher unless the part is sanded or chemically smoothed.

I would use injection moulding for a product going into mass production — for example, the casing of a smartphone manufactured in millions of units. I would use 3D printing for prototyping — testing the shape and fit of that same phone casing before committing to the expensive injection mould. The two processes are complementary: 3D print to test, injection mould to mass-produce.

Exam question: "A manufacturer wants to produce a lightweight, waterproof casing for an outdoor security camera. The casing must be produced in quantities of 50,000 per year. Name a suitable material and justify your choice. [4 marks]"

Top-mark answer:

I would use ABS (acrylonitrile butadiene styrene) — a thermoplastic. [1 mark — material named correctly]

ABS is lightweight (density ~1.05 g/cm³) which meets the lightweight requirement, and it is waterproof — it does not absorb water or degrade in outdoor conditions, protecting the electronics inside. [1 mark — two properties linked to the specification]

ABS is a thermoplastic, which means it can be injection moulded. This is ideal because injection moulding is designed for mass production — with 50,000 units per year, the high tooling cost is spread over many units, making the per-unit cost very low. [1 mark — manufacturing process matched to production scale]

ABS also has good impact resistance — important for an outdoor camera that may be hit by objects or vandalised — and can be UV-stabilised with additives to prevent degradation from sunlight. [1 mark — additional relevant property with justification]

Exam question: "A company wants to design a portable, foldable laptop stand for students. Using notes and sketches, design a stand that: is lightweight and foldable, adjusts to 3 heights, is stable on a desk, suits 11"–16" laptops, and uses sustainable materials. [20 marks]"

Top-mark approach (showing one of the required annotated sketches):

         SIDE VIEW (folded position — 25mm thick)
    ┌──────────────────────────────┐
    │  BASE PLATE (3mm birch      │ ← 300mm × 240mm
    │  plywood — FSC certified)   │
    │                              │    "Plywood chosen because
    │  ┌─────┐          ┌─────┐   │     cross-grain layers give
    │  │     │  hinge   │     │   │     strength in both directions
    │  │ LEG │──────────│ LEG │   │     — prevents warping with
    │  │     │          │     │   │     laptop heat. FSC certified =
    │  └──┬──┘          └──┬──┘   │     sustainable source."
    │     │ hinge           │ hinge│
    └─────┴─────────────────┴─────┘

Annotations that would accompany this sketch:

• Legs pivot on 4mm stainless steel hinge pins — stainless chosen for corrosion resistance and strength for repeated use
• Three height positions: 80mm, 120mm, 160mm — achieved by rotating legs to different locking notches. Covers the 5th–95th percentile eye-level range for students aged 14–18 (based on anthropometric data)
• Rubber feet (recycled silicone) on base plate — prevents slipping on desk surface. 2mm thick to absorb vibration from typing
• Total weight: approximately 380g — within the lightweight brief, fits in a standard backpack laptop sleeve
• Ventilation slots (6mm wide, spaced 15mm apart) aligned with laptop intake vents — prevents overheating

Context: "Storage solutions for small living spaces" | User group: HK secondary students with small bedrooms

Interview 1 — Jason, Y11 student, 380 sq ft apartment (shared with 4 family members)

"My desk is also where I eat, so it's always cluttered. I have textbooks, a laptop, stationery, and sometimes food containers all fighting for space. The biggest problem is I can't find things quickly — my highlighters are always buried under papers. I've tried desk organisers from Japan Home but they take up too much of the actual desk surface. What I need is something that goes UP, not across — like using the wall or the back of the desk."

Key insight: User doesn't need more storage volume — he needs vertical organisation that preserves desk surface area. This changes the design direction from "make a bigger organiser" to "make an organiser that mounts on the wall/desk edge."

Interview 2 — Mei, Y10 student, 450 sq ft apartment

"My desk is in my bedroom which is also the living room when my parents have guests. So my stuff needs to look neat — not like a messy student desk. I want something that can close up or look tidy when I'm not studying. Also, I do art as well as homework, so I have two completely different sets of stuff — art supplies and school supplies — and they don't fit together."

Key insight: Dual-function user — needs modular/compartments that separate art supplies from school supplies. Aesthetic requirement: must look presentable when not in use (not just functional).

Design Brief: "I will design and make a wall-mounted, modular desk organiser for HK secondary students living in small apartments, that separates school supplies from other items, preserves desk surface area, and looks neat when not in use."

Shows the development of the shelf bracket from initial idea to final design

Teacher said: "Draw a demand and supply diagram for the market for smartphones. Then show the effect of: (a) a new model being released, (b) a rise in component costs. Label everything clearly. Write one sentence explaining each shift."

Price ▲        S
       │       /|
       │      / |        (a) New model released →
  P2 ──│─────●──|──        demand increases (D1→D2)
       │    /|  |          because consumer preferences
  P1 ──│───●─|──|──        shift toward the new model.
       │  /| |  |          Price ↑ from P1 to P2.
       │ / | |  |  D2      Quantity ↑ from Q1 to Q2.
       │/  | |  |
       │   | |  |  D1
       └──────────────► Qty
          Q1 Q2

Price ▲       S2
       │      /| S1         (b) Component costs rise →
       │     / |            supply decreases (S1→S2)
  P2 ──│────●──|──          because it's more expensive
       │   /|  |            to produce each phone.
  P1 ──│──●─|──|──          Price ↑ from P1 to P2.
       │ / |  |  |          Quantity ↓ from Q1 to Q2.
       │/  |  |  |
       │   |  |  |  D1
       └──────────────► Qty
          Q2 Q1

Teacher said: "A cinema raises ticket prices from £10 to £12. Ticket sales fall from 500 to 400 per day. Calculate PED. Is demand elastic or inelastic? Should the cinema raise or lower prices to increase revenue? Show all working."

Student answer (full marks):

Step 1: Calculate % change in price
%ΔP = (New − Old) ÷ Old × 100 = (12 − 10) ÷ 10 × 100 = 2 ÷ 10 × 100 = 20% increase

Step 2: Calculate % change in quantity demanded
%ΔQd = (New − Old) ÷ Old × 100 = (400 − 500) ÷ 500 × 100 = −100 ÷ 500 × 100 = −20% (a 20% decrease)

Step 3: Calculate PED
PED = %ΔQd ÷ %ΔP = −20% ÷ 20% = −1 (absolute value = 1, so demand is UNITARY ELASTIC)

Step 4: Revenue analysis
Original revenue = £10 × 500 = £5,000
New revenue = £12 × 400 = £4,800
Revenue fell by £200. This means raising prices reduced total revenue.

Step 5: Recommendation
Since PED = 1 (unitary), any price change will reduce total revenue — the % change in Qd exactly offsets the % change in P. The cinema should keep prices at £10. If they want to increase revenue, they should focus on non-price strategies: improve the cinema experience (better seats, better screen), offer loyalty cards, or sell more concessions (popcorn, drinks) which have different PED values.

Teacher said: "Write one paragraph evaluating whether taxing polluting firms is an effective way to reduce pollution. Include a diagram, consider both advantages and disadvantages, and reach a conclusion. [8 marks]"

Student answer (top marks):

A tax on pollution-causing activities aims to internalise the negative externality — making the polluter pay the social cost rather than just the private cost. The tax shifts the supply curve left (from MPC to MPC+tax, closer to MSC), reducing output from the market quantity Qm to a lower quantity closer to the social optimum Qs. This is economically efficient because it uses the price mechanism rather than outright bans — firms that can reduce pollution cheaply will do so, while those that find it very expensive will pay the tax instead, achieving the reduction at the lowest total cost to society. [3 marks — mechanism explained + efficiency argument]

However, the effectiveness of a pollution tax depends crucially on the price elasticity of demand for the polluting good. If demand is inelastic (for example, petrol — people need to drive to work), the tax may barely reduce quantity at all — consumers absorb the price increase rather than changing behaviour. In this case, the tax becomes mainly a revenue-raiser for the government rather than an effective environmental policy. [2 marks — limitation: PED]

There are also practical difficulties: measuring the exact level of pollution to set the tax at the right rate is technically challenging — set it too low and pollution barely falls, set it too high and firms may relocate to countries with weaker environmental laws (carbon leakage), actually increasing global emissions. [2 marks — practical limitations]

Overall, taxation can be an effective tool when demand is elastic, pollution is easily measurable, and the tax is combined with complementary policies — for example, using the tax revenue to subsidise green alternatives (electric vehicles, renewable energy). The UK's Climate Change Levy on businesses, combined with renewable energy subsidies, has contributed to a ~50% reduction in UK territorial emissions since 1990 — suggesting that a well-designed tax, as part of a policy mix, can work. [1 mark — judgement with specific example]

Exam extract: "Figure 1 shows the price of avocados rose from $1.20 to $2.80 per fruit between 2020 and 2023. Over the same period, global consumption increased from 6 million tonnes to 11 million tonnes." Question: "Using a demand and supply diagram, explain why both the price and quantity of avocados increased. [6 marks]"

Model answer:

When both price AND quantity increase simultaneously, this can only be explained by an increase in demand — a rightward shift of the entire demand curve. If supply had increased, price would FALL (not rise). If supply had decreased, quantity would FALL (not rise). Only a demand increase produces both P↑ and Q↑. [2 marks — identifies cause as demand increase through elimination]

Price ▲          S
       │         /|
  $2.80│────────●─|── D2
       │       /| |
  $1.20│──────●─|─|── D1
       │     /| | |
       │    / | | |
       └──────────────► Qty (tonnes)
          6M   11M

[2 marks — correctly drawn diagram with both equilibria labelled]

The likely cause of this demand increase is rising global popularity of avocados — they became a health food trend on social media (Instagram, TikTok), shifting consumer tastes and preferences. Additionally, rising incomes in developing countries (avocados are a normal good with positive YED) increased the number of consumers who could afford them. [2 marks — two plausible causes linked to demand shift factors]