The rule is short, the consequences are long, and the tool below drills it from your own notes.
WeSolve+ reads the whole document and writes the questions for you
Upload your PDF, photograph your notebook, or point the camera. WeSolve+ writes questions from that material, explains why each answer is right, reads the chapter back to you as a podcast, and remembers every item you missed until you own it.
The tool below is a small browser-only tool and it is not WeSolve+: paste a few lines and text rules turn them into cards on the spot. The real app, the one that uses AI, is behind the link above.
Shifters, from your own notes
This is a browser-only tool, and that is all it isIt splits the text you paste by rule, and nothing else. WeSolve+ is a different thing entirely: it reads your whole PDF with AI, writes the reasoning behind every question, speaks the chapter back to you, and remembers what you missed so it can return it. Try the real app now, free!
This tool splits the text you paste by rule and returns cards. It cannot draw or read a graph, so it works on the definitions you already wrote down.
The rule, and it is one sentence
A change in the good's own price moves you along the curve. Anything else shifts the whole curve. That is the entire distinction, and supply and demand questions are built to test whether you apply it under time pressure rather than whether you can recite it.
Substitutes and complements are shifters, not exceptions
A rise in the price of coffee shifts the demand curve for tea, because tea's own price did not change. Students often treat this as a special case and get tangled; it is the rule working normally. Asking whose price changed, and whether that good is the one on the axis, resolves almost every one of these.
Two shifts at once need a stated ambiguity
When supply and demand both move, one of price or quantity is determined and the other is ambiguous without knowing the relative sizes. Saying so explicitly is the correct answer, not a hedge. Questions include these deliberately, and an answer that picks a direction anyway is marked wrong for guessing.
Ceilings and floors only matter when they bind
A price ceiling above the equilibrium price does nothing at all, and a floor below it does nothing either. The word binding is doing real work, so read the diagram before answering. A ceiling that binds sits below equilibrium and produces a shortage.
Elasticity is why the same shift has different consequences
Elasticity decides how much of a shift lands on price and how much on quantity, and later it decides who bears a tax. Introduced here, it is the bridge between this unit and most of the rest of the course, so it repays being learned as a concept rather than as a formula.
What to photograph for Supply and Demand
Curves with your shift arrows and a reason beside each. Related: Macroeconomics Unit 1, quiz options and pricing.
Sources used on this page
- College Board, AP Microeconomics
- Supply and demand
- Elasticity (economics)
- Price ceiling
- Opportunity cost
- Active recall
- Spaced repetition
- Testing effect
- Forgetting curve
- Generation effect
- Judgment of learning
- Metacognition
- Desirable difficulty
- Distributed practice
- Formative assessment
- Flashcard
- Cloze test
- Multiple choice
- Test (assessment)
- Educational assessment
- Advanced Placement
- Curriculum
- Study skills
- Study guide
- Note-taking
- Overlearning
- Instructional scaffolding
- Item analysis
- Mastery learning
| Event | What happens | Why |
|---|---|---|
| The good's own price rises | Movement along | Price is on the axis |
| Income rises, normal good | Demand shifts right | Not the good's own price |
| Substitute's price rises | Demand shifts right | Not the good's own price |
| Input cost rises | Supply shifts left | Not the good's own price |
| Both curves move | One outcome ambiguous | Depends on relative sizes |
| Ceiling above equilibrium | Nothing | It does not bind |
What is AP Microeconomics Unit 2?
Supply and Demand: equilibrium, the shifters of each curve, price controls, and an introduction to elasticity.
What is the difference between a shift and a movement?
A change in the good's own price moves you along the curve. Anything else shifts the whole curve. That single sentence carries the unit.
Why do substitutes confuse people?
Because they feel like an exception. They are not: the other good's price changed, not the one on the axis, so the curve shifts as normal.
What do I do when both curves shift?
State which outcome is determined and say the other is ambiguous without the relative sizes. That is the correct answer, not a hedge.
When does a price ceiling matter?
Only when it binds, meaning it sits below the equilibrium price. Above equilibrium it does nothing at all.
Why is elasticity introduced here?
Because it decides how much of a shift lands on price and how much on quantity, and later who bears a tax. It bridges to most of the course.
Last updated: 2026-08-15