Economics graphs explained step by step
Build the graph in front of the student: axes, each curve as it's named, the equilibrium, then the shift. Where students lose marks and how to explain it.
By the Chasca team 5 min read
An economics graph is easiest to follow when it is built in front of the student: the axes first, each curve as it is named, the equilibrium where they cross, then the shift and the new equilibrium, with what happened to price and quantity said in words. Exam reports show that marks slip away when labels, shifts and shaded areas go wrong.
Where do students go wrong with economics graphs?
The College Board’s reports on the AP Microeconomics exam show it plainly. In 2025, when 118,022 students’ answers were scored, 73% of responses to one question earned the point for a correctly labelled supply and demand graph with the equilibrium price and quantity marked. Common errors included missing or switched curve labels. Later in the same question, 63% correctly showed how a subsidy shifts supply, and 8% shaded the right area for what the subsidy costs the government. Many responses also mixed up supply with quantity supplied.
The report encourages teachers not only to model these graphs but to have students practise drawing them.
Do graphs help students learn economics?
Not on their own. In two experiments at the University of South Carolina, Elchanan Cohn and colleagues randomly assigned principles-of-economics students to the same lecture with graphs or without them. In 1995, the students who saw the graphs gained significantly less; in 1997, there was no difference. A finished graph with several curves on it is a lot to decode at once.
How the graph appears seems to matter more. In a 2023 study with 133 secondary school students, Sascha Schneider and colleagues found that diagrams drawn progressively during the narration led to better recall and transfer than the same pictures shown finished; we summarise that and related findings in why whiteboard videos work. And Paul Ginns’ 2006 meta-analysis of 50 studies found that bringing related information together, in space and in time, gives substantial learning gains for complex material, which is what a graph and its explanation are.
How do students learn graphs today?
From textbook figures that show the finished graph, lecture slides, revision guides and tutors. The hard parts are the same everywhere:
- Which curve moves, and which way. A frost hits supply; a fashion hits demand.
- A shift versus a movement along a curve. Demand and quantity demanded are not the same thing, as the AP report shows.
- Numbers that agree. If the curves come from equations, every point on the graph should satisfy them, and a sketched graph often doesn’t.
- Areas. Surplus, tax revenue and deadweight loss are easy to shade wrongly when they appear all at once.
What should a graph explanation show?
- Axes first: price up the side, quantity along the bottom.
- Each curve drawn as it is named, and labelled at once.
- The equilibrium where they cross, with dashed guides to the price and quantity, and their values said.
- The cause of the shift, then the new curve, labelled, and the new equilibrium.
- What happened, in words: price rises from 4 to 6, quantity from 12 to 18.
- Areas shaded only when they are named, one at a time.
- Numbers that match the working, so the graph and the algebra tell the same story.
What does that look like for one problem?
Take demand Qd = 20 − 2P and supply Qs = 3P. Setting them equal gives 20 − 2P = 3P, so P = 4 and Q = 12: that point is marked where the curves cross, with guides to 4 on the price axis and 12 on the quantity axis. Now demand rises to Qd = 30 − 2P. The new demand curve is drawn to the right of the old one, the new crossing is found the same way (30 − 2P = 3P, so P = 6 and Q = 18), and the explanation ends in words: the rise in demand pushed the price up from 4 to 6 and the quantity from 12 to 18. Supply didn’t shift; the market moved along it. Because every point on the graph satisfies its equation, the picture and the algebra can’t disagree.
What does the Economics problems skill do?
We make Chasca, so take our part of this with that in mind. The Economics problems skill works economics problems on a teacher’s board, with the graph drawn beside the working:
- Type the problem with the curves’ equations or numbers, or add photos, a PDF or a document of the sheet: supply and demand, elasticity, costs and revenue, surplus and tax, and national income numericals.
- Every curve is drawn from its equation, so the graph is exact and its crossing points match the working.
- The graph is built as it is explained: the axes, each curve as it is named, the equilibrium with guide lines, then the shifted curve, dashed and labelled, and any surplus, tax or deadweight-loss area shaded as it comes up.
- What changed is said plainly, price and quantity before and after, and the answer is boxed. A numerical such as elasticity ends with what the number means, such as elastic, so a price rise cuts revenue.
- Curve labels follow the video’s language: D and S in English, D and O in Spanish, Portuguese and French, N and A in German, ط and ع in Arabic.
- Every answer is solved a second time, separately. If anything disagrees, or disagrees with your key, the video’s page tells you which question to check.
- The narration is in your language, in any of 30 narrators or your own voice.
Who is it for?
Economics teachers preparing students for AP, A level, IB and school-leaving exams, tutors, and lecturers on principles courses who want every problem on a sheet worked as a graph, not as a paragraph.
What won’t it do?
- Draw a curve that doesn’t match its numbers.
- Draw shift arrows yet. The shifted curve is dashed and labelled instead.
- Guess an answer it can’t check. A disagreement is shown to you, never hidden.
- Write essays or argue policy. It works problems.
How do you make one?
- Open Economics problems in Chasca.
- Type the problem with its equations or numbers, or add a photo or PDF of the sheet.
- Pick the language, the voice and a black board or whiteboard, then make the video.
- Check the video’s page for any flagged question before you share it.
Your first two videos are free, up to a minute each, watermarked and with no card required; a free video works the first problems that fit in its minute. Plans start at $9.99 a month (pricing).
Sources
- College Board (2025). Chief Reader Report on Student Responses: 2025 AP Microeconomics Free-Response Questions, Set 2.
- Cohn, E., Cohn, S., Balch, D. C., & Bradley, J., Jr. (2001). Do graphs promote learning in principles of economics? The Journal of Economic Education, 32(4), 299–310.
- Schneider, S., Krieglstein, F., Beege, M., & Rey, G. D. (2023). Successful learning with whiteboard animations: A question of their procedural character or narrative embedding? Heliyon.
- Ginns, P. (2006). Integrating information: A meta-analysis of the spatial contiguity and temporal contiguity effects. Learning and Instruction, 16(6), 511–525.
Video transcript What the narrator says in the 1:45 explainer above.
In this video, we find market equilibrium and explain how rising demand changes price and quantity.
Question one. Q d equals twenty minus two P and Q s equals three P. Find the equilibrium price and quantity. Then demand rises to Q d equals thirty minus two P: find the new equilibrium and explain what happened to price and quantity.
Put quantity on the horizontal axis and price on the vertical axis. Draw demand D, sloping down, and supply S, sloping up. At equilibrium, quantity demanded equals quantity supplied, so twenty minus two P equals three P.
Rearranging gives five P equals twenty, so the equilibrium price is four.
Substituting into supply, three times four gives an equilibrium quantity of twelve.
Mark their intersection as E one, at quantity twelve and price four. Now demand shifts right to D one because buyers demand more at every price. Set thirty minus two P equal to three P for the new equilibrium.
Five P equals thirty, so the new equilibrium price is six.
Supply now gives three times six, so the new equilibrium quantity is eighteen.
Mark E two at quantity eighteen and price six. Price rises from four to six, and quantity rises from twelve to eighteen. Notice that supply has not shifted; the higher price causes a movement along supply.
Hence, the original equilibrium is price four and quantity twelve; the new equilibrium is price six and quantity eighteen.
Questions people ask
Put price on the vertical axis and quantity on the horizontal one, draw demand sloping down and supply sloping up, label both, and mark the equilibrium price and quantity where they cross with dashed lines to each axis.
A change in the good's own price moves along the curve and changes the quantity demanded. A change in anything else, such as income or the price of a substitute, shifts the whole curve and changes demand.
Missing or switched labels, shifting the wrong curve and shading the wrong area. On one 2025 AP Microeconomics question, 73% of responses drew a correctly labelled market graph, and 8% shaded the correct area for the cost of a subsidy.
Set quantity demanded equal to quantity supplied, solve for the price, then put that price back into either equation to find the quantity. For Qd = 20 − 2P and Qs = 3P, the equilibrium is P = 4 and Q = 12.
Yes. The Economics problems skill draws each curve from its equation, marks the equilibrium with guide lines, dashes the shifted curve and shades surplus or tax areas as each is explained.
