AP Microeconomics / Basic Economic Concepts
Lesson
Scarcity, trade-offs, and the PPC
A production possibilities curve turns a trade-off into a picture.
Learning goals
- Define opportunity cost with a concrete alternative.
- Interpret points on, inside, and outside a PPC.
Explanation
Scarcity means you cannot have every good in unlimited amounts. Choosing more of one thing means choosing less of another. Opportunity cost names that next-best alternative, not every option you can imagine.
A production possibilities curve shows combinations of two goods that fully use current resources and technology. Points on the curve are efficient. Points inside waste resources. Points outside are not reachable yet. Growth later can push the curve out.
Key terms
- Opportunity cost. The value of the next-best alternative given up when a choice is made.
- Production possibilities curve. A model of the maximum combinations of two goods an economy can produce with current resources and technology.
Common mistakes
- Calling every unused option the opportunity cost, not the next-best one.
- Labeling an inside point “impossible” instead of inefficient.
Practice
Original Marlow Works items. Check the answer explanation after you try.
Maya can spend Saturday tutoring for $80 or painting a mural that she values at $50 of enjoyment (and she cannot do both). What is her opportunity cost of tutoring, and why?
Original Marlow Works item — not a College Board question.
Take your time—this is practice, not a test.
Answer explanation
A point lies inside a PPC. What does that say about resources?
Answer. Some resources are idle or misallocated, so more of one or both goods could be produced.
The frontier is the efficient boundary. Inside the frontier, you are leaving capacity unused.
Related resources
External links with reuse status. Marlow Works is independent and does not copy restricted exam or textbook material.
Official / link only
AP Microeconomics course page
Official six-unit framework for markets, costs, and market failure.
College Board · All rights reserved · accessed 2026-10-01
Open sourceCC BY — attribution required
Principles of Microeconomics: Scarcity and Social Provisioning
Open microeconomics background for scarcity, markets, and elasticity.
Open Textbook Library listing · CC BY · accessed 2026-10-01
Open source