AP Microeconomics Study Guide

The course starts with basic economic concepts — scarcity, opportunity cost, the production possibilities curve, comparative advantage, and marginal analysis, the way of thinking the whole course runs on. Supply and demand follows: how markets reach equilibrium, elasticity, consumer and producer surplus, and the effects of price controls and taxes.

The core of the course is the theory of the firm. Production, cost, and the perfect competition model covers costs, marginal revenue and marginal cost, and how a competitive firm decides how much to produce in the short and long run. Imperfect competition extends that to monopoly, oligopoly (including game theory), and monopolistic competition. Factor markets applies supply-and-demand thinking to labor and other inputs, where firms hire up to marginal revenue product. The course closes with market failure and the role of government — externalities, public goods, and the case for and limits of government intervention. Graphs are central; the exam expects you to draw firms and markets and read them precisely.

The College Board publishes approximate weightings as ranges, and the firm-and-market material dominates:

• Production, Cost, and the Perfect Competition Model — among the heaviest, roughly a fifth to a quarter of the multiple-choice section.
• Supply and Demand — also among the heaviest, roughly a fifth to a quarter.
• Imperfect Competition — substantial, in the mid-teens to low-twenties percent range.
• Basic Economic Concepts — moderate, in the low-to-mid teens percent.
• Factor Markets — moderate, roughly ten to thirteen percent.
• Market Failure and the Role of Government — the lightest, roughly eight to thirteen percent.

The takeaway: supply-and-demand plus the models of firm behavior (perfect and imperfect competition) can carry well over half the exam. If your time is tight, get the competitive-firm graphs and elasticity rock-solid first — the imperfect-competition and factor-market units lean on the same marginal logic.

Micro is a modeling exam built on marginal thinking, so make the graphs automatic:

1. Draw first, explain second. A correctly drawn and labeled firm or market diagram is usually most of the answer. Practice the perfectly competitive firm, monopoly, and a labor market until they're reflexive.
2. Live by the margin. Almost every decision in the course is "produce or hire up to where marginal benefit equals marginal cost." Anchor your reasoning there and the units connect.
3. Practice profit and surplus areas. Know how to identify profit, loss, deadweight loss, consumer and producer surplus on a graph — these are frequent point-earners.
4. Work mixed sets. The real difficulty is choosing the right model; mixing units once the basics are in place is the fastest way to surface gaps.
5. Review with full solutions, including why each wrong answer was tempting.

• Confusing the cost curves, especially average total cost, average variable cost, and marginal cost, and where they intersect.
• Mislabeling graphs on the free-response section — an unlabeled axis or curve forfeits points even when the shape is right.
• Mixing up the market structures, such as applying perfect-competition pricing to a monopoly.
• Forgetting that price equals marginal revenue only under perfect competition — a trap that breaks many imperfect-competition questions.
• Misreading elasticity, or treating a movement along a curve as a shift of the curve.
• Stopping reasoning at quantity when the prompt also wants price, profit, or deadweight loss.

Every unit below has a focused practice set with full written explanations and a rationale for every wrong choice, plus a worked-solutions page you can read straight through. Start with supply-and-demand and the perfect-competition model — the highest-leverage material — then take a mixed set across the whole subject to test whether you can pick the right model and read its graph under pressure. It's free and needs no account.