College Board-Aligned Original Notes

AP Macroeconomics Unit 3 Topic 3: Equilibrium and changes in the Aggregate Demand-Aggregate Supply Model

Explain Equilibrium and changes in the Aggregate Demand-Aggregate Supply Model by identifying decision-makers, incentives, constraints, and graph shifts.

Unit 3: National Income and Price Determination. College Board exam weighting listed for this unit: 17%-27% of exam score.

What to Know

Know what each curve represents before deciding whether it shifts.
Separate short-run and long-run effects when the model requires it.
Label axes, curves, equilibrium points, and the direction of change.
Always connect this topic back to the larger unit: National Income and Price Determination.

Detailed Notes

Equilibrium and changes in the Aggregate Demand-Aggregate Supply Model should be analyzed as a chain of cause and effect. Identify the initial condition, the change, the affected model, and the final outcome.

In AP Macroeconomics, graphs are not decoration. Curves represent behavior or constraints, so every shift or movement should match an economic explanation.

For AP-style answers, label the graph clearly and write the story in words: who responds, what changes, why the model moves, and what happens to price, quantity, output, employment, interest rates, or welfare.

Key Vocabulary

Scarcity

The condition of limited resources and unlimited wants.

Opportunity cost

The value of the next-best alternative given up when a choice is made.

Comparative advantage

The ability to produce a good or service at a lower opportunity cost.

Equilibrium

A market condition where quantity supplied equals quantity demanded.

Elasticity

A measure of how responsive one variable is to a change in another.

GDP

The market value of final goods and services produced within a country in a given period.

Quick Practice

How would you explain Equilibrium and changes in the Aggregate Demand-Aggregate Supply Model in one or two AP-style sentences?

Name the concept, apply it to a specific example or source, and explain the reasoning that connects the evidence to your answer.