Ten lessons that follow the six course units: economic concepts, indicators, AD-AS, money and banking, long-run policy and the open economy, with graph and free-response habits.
A reasoning guide to AP Macroeconomics, not a full course. Unit order and weightings follow the College Board course page; all numbers in examples are invented for practice.
Basic algebra and graph reading.
Course outline
Scarcity, trade-offs and the production possibilities curve
Use opportunity cost, comparative advantage and the PPC to reason about choices.
Measuring the economy: GDP, unemployment and inflation
Calculate GDP, unemployment and inflation measures and interpret them correctly.
Aggregate demand, aggregate supply and the price level
Use the AD-AS model to explain output and price level changes.
Multipliers and fiscal policy
Calculate spending multipliers and judge fiscal policy tools.
Money, banks and the money market
Explain money functions, the money multiplier and interest rate determination.
Monetary policy and central bank tools
Trace how central bank actions affect interest rates, investment and output.
Long-run effects: Phillips curve, growth and crowding out
Separate short-run trade-offs from long-run limits.
Open economy: exchange rates and the balance of payments
Use foreign exchange markets and the balance of payments to analyse international flows.
Policy mix: fiscal, monetary and the lag problem
Compare fiscal and monetary responses to the same gap and explain why timing matters.
Exam day: macroeconomics graphs and free response
Use the exam format and graph habits to score on the free-response questions.
Sources and curriculum note
Reviewed October 5, 2026. Confirm format on the College Board site for your exam year.
Read every lesson below. The interactive reader above contains the same explanations, with visual tools and quizzes.
1. Scarcity, trade-offs and the production possibilities curve
Learning goal: Use opportunity cost, comparative advantage and the PPC to reason about choices.
Unit 1 is the base of both economics courses. Scarcity means wants exceed resources, so every choice has an opportunity cost: the value of the next best alternative given up. A production possibilities curve shows the maximum combinations of two goods an economy can produce with fixed resources and technology. Points on the curve are efficient, points inside show unused resources or unemployment, and points outside are not reachable today.
A straight PPC means constant opportunity cost. A bowed-out curve means increasing opportunity cost, because resources are not equally good at making both goods. Economic growth, from more resources or better technology, shifts the curve outward. A change that helps only one good, such as a new farming technique, pivots the curve on one axis only. A move along the curve is a trade-off, while a shift of the curve is growth or loss of capacity.
Comparative advantage means producing a good at a lower opportunity cost than someone else. It, not absolute advantage, decides who should specialise. If country A gives up 2 units of cloth for 1 unit of wheat and country B gives up 4, then A has the lower opportunity cost of wheat and B has the lower opportunity cost of cloth. Both gain when each specialises and trades at a price between the two opportunity costs. The numbers in this lesson are invented for practice.
The circular flow model shows households selling resources to firms in factor markets and buying goods in product markets, with money flowing the opposite way. Marginal analysis, comparing marginal benefit with marginal cost, applies to every decision: do more of an activity while the marginal benefit is at least the marginal cost. Sunk costs are already spent and should not change the decision. Keep each economic term tied to a specific example when you write an exam answer.
Worked example
In one hour A makes 6 shirts or 3 hats; B makes 4 shirts or 4 hats (invented numbers). Who has the comparative advantage in hats?
A gives up 2 shirts per hat (6/3).
B gives up 1 shirt per hat (4/4).
B has the lower opportunity cost of hats.
So B has the comparative advantage in hats, and A in shirts.
Practice problem and solution
Moving along a PPC gives up 10 cars to gain 5 trucks. What is the opportunity cost of one truck in cars?
Common trap: Confusing absolute advantage with comparative advantage.
2. Measuring the economy: GDP, unemployment and inflation
Learning goal: Calculate GDP, unemployment and inflation measures and interpret them correctly.
Unit 2 covers 12% to 17% of the multiple-choice section. Gross domestic product, GDP, is the market value of final goods and services produced within a country in a year. On the expenditure side, GDP = C + I + G + (X − M): consumption, investment, government purchases and net exports. Intermediate goods are not counted, to avoid double counting, and neither are transfer payments or purely financial purchases such as stocks.
Nominal GDP uses current prices, while real GDP uses constant prices and so isolates changes in output. The GDP deflator is nominal GDP divided by real GDP times 100. Real GDP per person is a rough measure of living standards, though it leaves out unpaid work, leisure and environmental costs. The business cycle moves through expansion, peak, contraction and trough.
The unemployment rate is unemployed people divided by the labour force, where the labour force is the employed plus the unemployed who are actively looking. Discouraged workers who stopped looking are not counted as unemployed, so the rate can understate weakness. Frictional unemployment comes from job search, structural from skill or location mismatch, and cyclical from downturns. The natural rate of unemployment is the sum of frictional and structural, with no cyclical part.
The consumer price index measures the cost of a fixed basket of goods, and the inflation rate is the percentage change in the index. CPI can overstate inflation because of substitution bias and quality changes. Inflation hurts people on fixed incomes and lenders when it is unexpected, and it can help borrowers. The real interest rate is the nominal rate minus expected inflation. Always check whether a question asks for a level or a percentage change.
Worked example
Labour force is 200 and unemployed is 12 (invented). Find the unemployment rate.
Rate = unemployed / labour force.
12 / 200 = 0.06.
Convert to percent.
The unemployment rate is 6%.
Practice problem and solution
CPI rises from 200 to 210. What is the inflation rate in percent?
(210−200)/200 = 0.05, which is 5%.
Mental model: GDP counts final output. Real GDP removes price changes. Inflation is a percentage change.
Common trap: Counting intermediate goods or resales in GDP.
3. Aggregate demand, aggregate supply and the price level
Learning goal: Use the AD-AS model to explain output and price level changes.
Unit 3 carries 17% to 27% of the multiple-choice section. The aggregate demand curve shows the total quantity of real output demanded at each price level. It slopes down because of the wealth effect, the interest rate effect and the exchange rate effect. These are movements along AD caused by the price level. A shift of AD comes from changes in consumption, investment, government spending or net exports at any price level.
Short-run aggregate supply slopes up because some input prices are sticky, so higher prices raise profits and output. Long-run aggregate supply is vertical at potential output, where all resources are fully employed. SRAS shifts when input costs, productivity or expectations change, while LRAS shifts only when potential output changes, as with more capital, labour or technology.
Equilibrium is where AD meets SRAS. A recessionary gap means output is below potential; an inflationary gap means output is above potential. In the long run, flexible wages and prices push the economy back toward potential output. A demand shock, such as a fall in consumer confidence, moves price level and output in the same direction. A supply shock, such as an oil price spike, moves them in opposite directions, which is stagflation.
When drawing the model, label the axes price level and real GDP, label each curve, and show the shift with an arrow and the new curve. Then state the new price level and output compared with the old, in words. Do not confuse a shift with a movement along a curve. Another common slip is to shift LRAS when only SRAS has changed. If the question says short run, use SRAS; if long run, return to LRAS.
Worked example
An economy is at long-run equilibrium. Investment demand falls. What happens in the short run?
Lower investment reduces aggregate demand.
AD shifts left.
The price level and real GDP both fall.
Output is now below potential, a recessionary gap.
Practice problem and solution
If actual real GDP is 950 and potential is 1,000 (invented, in billions), what type of gap is it? Type recessionary or inflationary.
Output is below potential, so it is a recessionary gap.
Mental model: Name the curve, show the shift, state the effect on price and output.
Common trap: Mixing up a shift in a curve and a movement along it.
4. Multipliers and fiscal policy
Learning goal: Calculate spending multipliers and judge fiscal policy tools.
Fiscal policy is government spending and taxation used to influence the economy. Expansionary fiscal policy raises government spending or cuts taxes to shift AD right, while contractionary policy does the reverse. The marginal propensity to consume, MPC, is the share of an extra dollar of income that is spent. The marginal propensity to save, MPS, is 1 − MPC.
The spending multiplier is 1 / (1 − MPC), or 1 / MPS. An initial increase in spending becomes someone's income, a fraction of which is spent again, and so on. With an MPC of 0.8, the multiplier is 5, so a 10 unit rise in government spending raises equilibrium GDP by up to 50 units. The tax multiplier is smaller in size, −MPC / (1 − MPC), because part of a tax change affects saving instead of spending. The numbers here are invented for practice.
Automatic stabilisers, such as progressive income taxes and unemployment benefits, change the budget without new legislation: tax revenue falls and transfers rise in a recession. Discretionary policy needs deliberate action and suffers from time lags in recognising, deciding and acting. A budget deficit exists when spending exceeds tax revenue in a year, and the national debt is the accumulated sum of deficits.
Fiscal policy has limits. Government borrowing to finance a deficit can raise interest rates and reduce private investment, which is crowding out. Policy effects on the price level depend on where the economy sits on SRAS: large AD shifts near potential output raise prices more than output. Expectations also matter, since households that expect higher future taxes may save more. On an exam, state the policy, the curve it shifts, and the effect on output, prices and unemployment.
Worked example
MPC is 0.75 (invented). Government spending rises by 20. What is the maximum change in equilibrium GDP?
Multiplier = 1 / (1 − 0.75) = 4.
Change in GDP = 4 × 20.
Change = 80.
This is the maximum, before crowding out or leakages.
Practice problem and solution
If the MPC is 0.9, what is the spending multiplier?
Common trap: Using the spending multiplier for a tax change.
5. Money, banks and the money market
Learning goal: Explain money functions, the money multiplier and interest rate determination.
Unit 4 carries 18% to 23% of the multiple-choice section. Money acts as a medium of exchange, a unit of account and a store of value. Money supply measures such as M1 include cash and checkable deposits. Money is not the same as wealth or income. The demand for money rises when the price level or real GDP rises, and falls when the nominal interest rate rises, because holding money has the opportunity cost of lost interest.
Banks keep a fraction of deposits as reserves and lend the rest. The required reserve ratio sets the minimum. With a required reserve ratio of 10%, the simple money multiplier is 1 / 0.10 = 10, so new reserves of 100 can support up to 1,000 of new deposits, if banks lend all excess reserves and borrowers redeposit. The numbers are invented for practice. Excess reserves are held beyond the requirement, and holding more of them reduces the multiplier.
In the money market graph, the nominal interest rate is on the vertical axis and the quantity of money on the horizontal. Money demand slopes down. Money supply set by the central bank is a vertical line. If the money supply increases, the supply curve shifts right and the equilibrium interest rate falls. If money demand rises because of a higher price level, the interest rate rises. This graph links monetary policy to interest rates.
The loanable funds market is a separate model: savers supply funds, borrowers demand them, and the real interest rate balances the two. A government deficit increases demand for loanable funds and raises the real interest rate, and that is the crowding-out mechanism. Remember which graph you are using: money market for monetary policy and the nominal rate, loanable funds for saving, investment and the real rate. Label axes precisely.
Worked example
Reserve requirement is 20% and a bank receives a new 1,000 deposit (invented). What is the maximum change in total deposits?
Multiplier = 1/0.20 = 5.
Maximum change = 5 × 1,000.
Total deposits can rise by 5,000.
The 1,000 deposit is part of that 5,000.
Practice problem and solution
If the required reserve ratio is 25%, what is the simple money multiplier?
1/0.25 = 4.
Mental model: Money multiplier is 1 over the reserve ratio. Money supply shifts move the interest rate.
Common trap: Using the money market graph to analyse a government deficit.
6. Monetary policy and central bank tools
Learning goal: Trace how central bank actions affect interest rates, investment and output.
Monetary policy is the central bank's control of the money supply and interest rates. In the United States, the Federal Reserve uses open market operations, the discount rate, reserve requirements and the interest rate it pays on reserve balances. In an open market purchase the central bank buys bonds, banks gain reserves, the money supply rises and interest rates fall. A sale does the opposite. The College Board treats these tools as part of the Unit 4 content.
Expansionary monetary policy aims to close a recessionary gap: lower interest rates raise investment and interest-sensitive consumption, shifting AD right, so output rises and unemployment falls. Contractionary policy aims to reduce inflation by shifting AD left. The chain of effects, called the transmission mechanism, runs from money supply to interest rate to investment to AD. A break at any link weakens the effect, as when banks hold excess reserves instead of lending.
Lowering the discount rate makes borrowing from the central bank cheaper and encourages lending. Lowering the reserve requirement raises the money multiplier. Policy may face a zero lower bound where the interest rate cannot go much below zero, which pushes central banks to use other tools. Monetary policy has lags but can be decided faster than most fiscal policy since it is set by a central committee.
Exam answers need a full chain. For a recession, write: the central bank buys bonds, reserves rise, the money supply increases, the nominal interest rate falls, investment rises, AD shifts right, real GDP rises and the price level rises. For a policy comparison, state that monetary policy works through interest rates and investment while fiscal policy changes spending or taxes directly. Keep each step in the right direction and avoid skipping the interest rate link.
Worked example
Describe how the central bank would respond to high inflation.
It sells bonds in open market operations.
Reserves and the money supply fall.
The interest rate rises, so investment falls.
AD shifts left and inflation pressure eases, with output lower in the short run.
Practice problem and solution
Does selling bonds increase or decrease the money supply? Type decrease or increase.
Selling bonds removes reserves, so the money supply decreases.
Mental model: Buy bonds to expand, sell to contract. Follow the whole chain.
Common trap: Skipping the interest rate step.
7. Long-run effects: Phillips curve, growth and crowding out
Learning goal: Separate short-run trade-offs from long-run limits.
Unit 5 carries 20% to 30% of the multiple-choice section, the largest share. The short-run Phillips curve shows a trade-off between inflation and unemployment: when AD rises, output rises, unemployment falls and inflation rises. Moving along the curve is the result of a change in AD. A shift of the short-run curve comes from supply shocks or changes in expected inflation. A supply shock that raises costs shifts the curve up, giving higher inflation at each unemployment rate.
In the long run, the Phillips curve is vertical at the natural rate of unemployment. Attempts to hold unemployment below the natural rate raise expected inflation, which shifts the short-run curve up and brings unemployment back with higher inflation. The long-run curve shifts only if the natural rate changes, as when labour market institutions or matching improve. The AD-AS model and the Phillips curve tell the same story from different graphs.
Long-run economic growth comes from increases in potential output: more physical capital, more or better human capital, better technology and institutions. Policies that raise the savings rate or education may shift LRAS right. Real GDP growth is measured as a percentage change in real GDP, and per-capita growth subtracts population growth. The rule of 70, 70 divided by the growth rate in percent, estimates doubling time.
Government debt and deficits connect to the long run through interest rates. Deficits raise the demand for loanable funds, which can crowd out investment and reduce the capital stock, lowering potential growth. Supply-side policies, such as lower marginal tax rates or deregulation, aim to shift LRAS right. They may have effects over a long time, and results depend on details. Keep short-run and long-run statements separate, and say which one the question asks about.
Worked example
Real GDP grows at 3.5% per year (invented). Estimate the doubling time using the rule of 70.
Doubling time ≈ 70 / growth rate.
70 / 3.5 = 20.
About 20 years.
This is an estimate and assumes a constant growth rate.
Practice problem and solution
Using the rule of 70, how many years to double at 2% growth?
70/2 = 35 years.
Mental model: Short run has a trade-off. Long run is vertical at the natural rate.
Common trap: Treating the short-run Phillips trade-off as permanent.
8. Open economy: exchange rates and the balance of payments
Learning goal: Use foreign exchange markets and the balance of payments to analyse international flows.
Unit 6 carries 10% to 13% of the multiple-choice section. The exchange rate is the price of one currency in terms of another. The foreign exchange market graph for a currency shows demand and supply with the exchange rate on the vertical axis. Appreciation means the currency buys more foreign currency; depreciation means it buys less. Demand for a country's currency comes from foreign purchases of its goods, services and assets.
If US interest rates rise relative to other countries, foreigners want more US assets. Demand for dollars increases, the dollar appreciates, US exports become more expensive for foreigners and imports become cheaper, so net exports fall. If the dollar depreciates, net exports rise. Relative inflation matters too: a country with higher inflation than its partners tends to see its currency fall over time.
The balance of payments records transactions with the rest of the world. The current account contains goods and services trade, income and transfers. The financial account, often called the capital account in the course, records purchases and sales of assets. They sum to roughly zero, so a current account deficit is matched by a net inflow of capital. A country that imports more than it exports is financed by foreign investment into its assets.
Monetary and fiscal policy affect the open economy. Expansionary monetary policy lowers interest rates, which can reduce demand for the currency and depreciate it, boosting net exports and reinforcing the AD shift. Contractionary policy does the reverse. When analysing, work in order: policy, interest rate, capital flow, demand for the currency, exchange rate, net exports, AD. Use the correct label for each axis and name each direction of change.
Worked example
US interest rates rise relative to Europe's. What happens to the dollar and net exports?
Foreigners want to buy US assets with higher returns.
Demand for dollars increases.
The dollar appreciates.
US goods are costlier for foreigners, so net exports fall.
Practice problem and solution
If the dollar appreciates, do US net exports rise or fall? Type fall or rise.
A stronger dollar makes US exports more expensive and imports cheaper, so net exports fall.
Mental model: Interest rates drive capital flows, which drive the exchange rate and net exports.
Common trap: Treating a depreciating currency as always bad.
9. Policy mix: fiscal, monetary and the lag problem
Learning goal: Compare fiscal and monetary responses to the same gap and explain why timing matters.
Stabilisation policy tries to close output gaps. Facing a recessionary gap, the government can raise spending or cut taxes, and the central bank can lower interest rates. Both shift AD right. They differ in who decides, how fast they act and which sectors they favour. Fiscal policy needs legislation, so it can be slow to pass, but spending reaches the economy directly. Monetary policy can be changed at a meeting, but it works through borrowing decisions.
Lags matter. The recognition lag is the time to notice a problem, the decision lag the time to choose a policy and the impact lag the time for it to work. If policy takes effect after the economy has already recovered, it can push output above potential and raise inflation. For this reason, economists often prefer automatic stabilisers for the fast response and discretionary policy for large shocks. Data are revised after release, which adds to the difficulty.
The same gap can be closed with different policy mixes with different side effects. Tax cuts with easy money raise AD strongly and push interest rates down, while tax cuts with tight money raise AD but also raise interest rates and may crowd out investment. Spending cuts with easy money can reduce deficits while holding AD up. Each mix shifts the composition of output: tax cuts favour consumption, lower interest rates favour investment and net exports through depreciation.
When an exam question gives a scenario, identify the gap first, then list the available tools and the effect on AD, then say what happens to output, price level and unemployment in the short run. If the question asks about the long run, return to potential output and mention that these tools mostly affect the price level there. Finish with one limitation, such as a lag, crowding out or an expectations effect, if the question asks for evaluation. Keep each claim specific.
Worked example
An economy has a recessionary gap. List one fiscal and one monetary response and say the effect on AD.
Fiscal: raise government spending.
Monetary: buy bonds to lower interest rates.
Both raise aggregate demand.
AD shifts right, raising output and prices in the short run.
Practice problem and solution
Name the lag between a policy being chosen and its effects appearing. Type impact, decision or recognition.
Impact lag: the time for the policy to work.
Mental model: Same gap, different tools and lags.
Common trap: Assuming policy acts instantly.
10. Exam day: macroeconomics graphs and free response
Learning goal: Use the exam format and graph habits to score on the free-response questions.
The College Board's AP Macroeconomics exam page lists two sections. Section I has 60 multiple-choice questions in 1 hour 10 minutes, worth 66% of the exam score. Section II has three free-response questions in 1 hour including a 10-minute reading period, worth 33%: one long question worth 50% of the section and two short questions worth 25% each. Check the exam page for your year, since format and policy can change.
Free-response questions ask you to make assertions, explain concepts and models, perform numerical analysis and draw or interpret graphs. Short answers are scored on specific points, so answer exactly what is asked and stop. A one-line statement with the direction of change, such as 'the price level rises', earns the point; a paragraph that never states the direction does not.
For graphs, always label both axes, label every curve, mark the original equilibrium and the new one, and show shifts with arrows. Use dotted lines to the axes for equilibrium values. A graph with a correct shape but a missing label can lose the point. If the question asks you to draw, draw it even if you also explain in words; if it asks you to explain, write sentences that use the graph's terms.
Build chains in order. For a policy change, name the policy, the variable it moves, the curve that shifts and the final effect on real GDP, price level and unemployment. State the direction for each. Check that your short-run and long-run statements are not mixed. Use the reading period to underline the command words and the time frame in each part. If you are stuck on a numerical part, show the formula and substitution, since process can earn credit even if the arithmetic slips.
Worked example
Explain the effect of a tax cut on real GDP in the short run.
A tax cut raises disposable income.
Consumption increases.
AD shifts right.
Real GDP and the price level rise in the short run.
Practice problem and solution
The long free-response question is worth what percent of the free-response section? Enter a number.
The long question is 50% of the section; each short question is 25%.
Mental model: Label graphs. State directions. Build chains in order.
Common trap: Writing an explanation that never states the direction of change.