To explain a diagram in words, read it in a fixed order: market, axes, original equilibrium, what shifted and why, new equilibrium, and what that means. Writing one sentence for each step gives you a complete paragraph.
It fits into the SPM Economics learning guide, alongside using diagrams to support an answer.
What does this look like for you?
You draw the curves, label them, and put the arrow in the right place. Then the question says “Explain the diagram” and you write “The curve moves to the right”, which is true but is only a description. This page is about getting from the drawing to the sentences.
Why does the paragraph stall?
- You describe the shape, not the cause.
- You skip the labels on the axes, so the marker cannot see you read them.
- You leave out the original equilibrium, so the change has no starting point.
- You stop after the shift and never say what happened to the price and quantity.
The six-step sweep
- Name the market and the axes.
- State the original equilibrium.
- Say which curve shifted and in which direction.
- Give the cause of the shift in a short clause.
- State the new equilibrium.
- Say what changed, in price and in quantity.
A worked example
A diagram shows the market for kuih in a fictional town. The supply curve starts as S1 and shifts left to S2. The original equilibrium is RM1.50 for 400 pieces.
After the shift, it is RM1.80 for 340 pieces. A note says that the price of flour has risen.
A full explanation:
“The diagram shows the market for kuih, with price on the vertical axis and quantity on the horizontal axis. The original equilibrium is at RM1.50 and 400 pieces.”
“The rise in the price of flour increases sellers’ costs, so supply shifts left from S1 to S2. At the old price, quantity demanded now exceeds quantity supplied, so the price rises.”
“The new equilibrium is RM1.80 and 340 pieces, so the price is RM0.30 higher and 60 pieces fewer are traded.”
Check the arithmetic: 1.80 − 1.50 = RM0.30 and 400 − 340 = 60. The paragraph covers all six steps in five sentences.
The common mistake
The typical slip is to describe the picture, not explain it.
| Describes the picture | Explains the diagram | |
|---|---|---|
| Shift | “The supply curve moves left” | “Higher flour prices raise costs, so supply shifts left” |
| Result | (missing) | “Price rises from RM1.50 to RM1.80, quantity falls from 400 to 340” |
The explanation includes a reason and a result. Another habit is useful: say the equilibrium aloud before you write it. If you can say “price up, quantity down”, the sentence is half written.
What can I do this week?
Choose three diagrams from your textbook. For each, write one sentence per step on a card.
Then read only the card and sketch the diagram from it. If the sketch matches, your sentences carry the full information. Check your curve directions with the supply-demand diagram reasoning explorer and note slips in the mistake log.
For turning a chain of causes into a paragraph, see writing an Economics explanation instead of describing a picture.
When might one-to-one tuition help?
If you can explain aloud but freeze on paper, or the reverse, a teacher can listen to one version and help you map it onto the other. You then practise on your own diagrams, not generic ones.
Read about online one-to-one Economics tuition, or the one-hour trial class (from RM50), which is a real taught lesson.