Who this is for: Cambridge IGCSE Economics (0455) students who want demand — the law of demand, demand curves and the difference between movements and shifts — to become a reliable source of marks instead of a diagram they misread under exam pressure.
What query it owns: how to understand and revise demand in Cambridge IGCSE Economics.
Why this is safe: this page owns the demand revision-guide angle, while Tutopiya’s Demand subtopic page owns the learning resource and the free Demand quiz owns the practice.

Demand is the quantity of a good or service consumers are willing and able to buy at each price over a given time period. Cambridge IGCSE Economics (0455) expects you to state the law of demand, draw demand curves, and distinguish a movement along the curve (caused by price change) from a shift of the curve (caused by non-price factors). This guide links each idea to the diagram and explanation questions examiners set.

Key takeaways

• The law of demand states that, ceteris paribus, as price falls, quantity demanded rises — and vice versa.
• A demand curve slopes downward from left to right (inverse price–quantity relationship).
• A movement along the demand curve is caused by a change in the good’s own price.
• A shift of the demand curve is caused by non-price factors (income, tastes, substitutes, complements, population).
• Extension of demand = price falls, quantity demanded rises; contraction = price rises, quantity demanded falls.

What is demand in Cambridge IGCSE Economics?

Demand is the quantity of a product that consumers are willing and able to purchase at various prices during a specific period. Cambridge IGCSE Economics (0455) tests whether you can define demand precisely (willing and able), draw an accurate downward-sloping curve, and explain what causes demand to increase or decrease at every price level.

You can read the full explanation, diagrams and notes on Tutopiya’s Demand subtopic page before you attempt questions.

Core demand definitions you must know

Term	Definition	Diagram signal
Demand	Quantity consumers are willing and able to buy at each price	Entire curve or schedule
Quantity demanded	Amount bought at one specific price	A single point on the curve
Law of demand	Price and quantity demanded move in opposite directions	Downward-sloping curve
Extension of demand	More bought because own price fell	Movement down along the curve
Increase in demand	More bought at every price (non-price factor)	Curve shifts right

How to analyse demand — step by step

1. Draw axes — price on the vertical axis, quantity on the horizontal axis.
2. Plot the demand curve — downward-sloping, labelled D.
3. Identify the cause — has the good’s own price changed, or a non-price factor?
4. If own price changed — show a movement along (extension or contraction).
5. If a non-price factor changed — draw a parallel shift (increase = right; decrease = left).
6. State ceteris paribus — “all other things being equal” — when explaining the law of demand.

Test yourself with the free Demand quiz once you can separate movements from shifts every time.

Movement along vs shift of demand: the comparison that wins marks

Change	Cause	Diagram	Terminology
Movement along	Change in the good’s own price	Slide along existing D curve	Extension (price ↓) or contraction (price ↑)
Shift right	Non-price factor favourable to demand	Whole curve moves right	Increase in demand
Shift left	Non-price factor unfavourable to demand	Whole curve moves left	Decrease in demand

Non-price factors that shift demand

Factor	Increase in demand (shift right)	Decrease in demand (shift left)
Income (normal good)	Income rises	Income falls
Tastes/fashion	Good becomes fashionable	Good goes out of fashion
Substitutes	Price of substitute rises	Price of substitute falls
Complements	Price of complement falls	Price of complement rises
Population	Population increases	Population decreases

Demand in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical demand stem
Define	Precise economic meaning	”Define demand.”
Draw	Accurate labelled diagram	”Draw a demand curve for product X.”
Distinguish between	Clear comparison of two concepts	”Distinguish between a movement along and a shift of the demand curve.”
Explain	Cause and effect	”Explain why the demand curve slopes downward.”
Analyse	Break down factors with diagrams	”Analyse the effect of a rise in income on the demand for a normal good.”

Worked exam-style stems (how to answer the wording)

1. “Define demand.” Demand is the quantity of a good or service that consumers are willing and able to buy at each price over a given time period. Mark-scheme reward: willing + able + at each price.
2. “The price of coffee falls. Explain the effect on the quantity demanded of coffee.” Lower price causes an extension of demand — a movement down along the existing demand curve, so more coffee is bought. Reward: extension + movement along (not a shift).
3. “Consumers’ incomes rise. The good is a normal good. Explain the effect on demand.” Demand increases at every price — the demand curve shifts to the right. More is demanded at each price because consumers can afford more. Reward: shift right + link to income.

How demand connects to the rest of Cambridge IGCSE Economics

Demand pairs with Supply to determine Market Equilibrium. The Cambridge IGCSE Economics resource hub links every Allocation of Resources subtopic.

Common mistakes students make

• Using “demand rises” when only quantity demanded changes (own price change).
• Drawing an upward-sloping demand curve (violates the law of demand).
• Shifting the curve when the question only changes own price (should be a movement).
• Forgetting “willing and able” in the definition of demand.
• Confusing substitutes and complements when explaining shifts.

When you need more support

If demand diagram questions keep costing marks, work through the Demand quiz, then get focused help from a Cambridge IGCSE Economics tutor.

Frequently asked questions

Is demand hard in Cambridge IGCSE Economics? The core ideas are straightforward. Most marks are lost by confusing movements along the curve with shifts caused by non-price factors.

What is the law of demand? Ceteris paribus, as the price of a good falls, the quantity demanded rises, and vice versa.

What causes a shift in demand? Non-price factors: income, tastes, prices of substitutes and complements, population size and distribution.

How do I revise demand effectively? Practise labelling diagrams, list shift factors, then take the Demand quiz to check movements vs shifts.

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