Demand describes how much of a good buyers are willing and able to buy at each possible price, over a given period. This module teaches you to read demand schedules and curves, to tell a movement along a curve from a shift of the whole curve, and to build market demand from individual buyers.
It sits inside IGCSE Economics after scarcity, choice and opportunity cost and before supply and equilibrium. Cambridge Economics 0455 expects you to use demand ideas in short explanations and diagrams, so the habits you build here carry through the whole course.
What do you need before starting?
You need the idea that buyers face limited money and must choose. You also need basic graph reading: find a value on one axis, move across to the line, then read the other axis. Percentage change helps in some questions, and the percentage-base explorer is a quick way to practise it.
One orienting example
Imagine a fictional stall at Kampung Seri Market that sells iced lime tea. On a normal day buyers want these quantities:
| Price per cup (RM) | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|
| Cups demanded per day | 120 | 100 | 80 | 60 | 40 |
If the stall raises the price from RM4 to RM5, buyers move from 80 cups to 60 cups. That is a movement along the same demand curve, caused by the stall’s own price.
Now a heatwave arrives. At every price buyers want 30 more cups: RM4 now gives 110 cups and RM5 gives 90. The whole curve has shifted right, caused by something other than the price.
Two different causes, two different diagram changes. The rest of the module trains you to separate them quickly.
What order should you study the lessons in?
- Distinguish a movement along demand from a shift: the central idea, so start here.
- Explain a demand factor in a fictional market: learn the factors that cause a shift and how to write the chain of reasoning.
- Read quantity at a stated price: practise reading schedules and curves accurately, including between listed prices.
- Compare two demand curves with identical scales: learn why a fair comparison needs the same axes.
- Separate individual and market demand: add buyers together correctly.
- Finish with the mixed practice set, and log slips in the mistake log.
The demand, supply and shift explorer lets you move a curve and watch the table change, which suits lessons 1, 2 and 4.
What are the common traps?
- Saying “demand rises” when only the price fell. The correct phrase is “quantity demanded rises”.
- Shifting the curve when the price of the good itself changed.
- Reading the wrong axis, so a price is given as a quantity.
- Comparing two graphs drawn on different scales and calling one “steeper”.
- Adding prices instead of quantities when building market demand.
- Giving a factor with no chain, such as “income rises so demand shifts” without saying why buyers want more.
How should you use the practice set?
Attempt each question on paper before opening the answer. Write one full sentence of explanation, not just a letter or number. When you miss a question, the “If you got these wrong” section sends you to the right lesson. After a week, repeat only the ones you missed.
Individual teaching helps most when your diagrams are right but your explanations stop halfway. That is a common pattern, and our online one-to-one Economics tuition is built around spotting it in your own writing.