Unit 1: Foundations of Economic Thinking
Why scarcity forces every choice into a trade-off, how a curve traces the limits of what an economy can produce, and why trading anyway makes both sides richer.
12 topics · 42 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
What Economics Studies: Scarcity and Choice
- How it worksHow does limited time, labor, and resources force every person to choose one option over another?
- How it worksWalk me through how economics turns scarcity into a formal study of the choices people make.
- Common mistakeWhy isn't scarcity a problem that only shows up in poor countries or for poor people?
- Going furtherWhat happens to the range of choices available when a resource everyone needs becomes more scarce?
Your turn1 of 2
A billionaire can buy almost anything he wants, yet economists still say his time is scarce. Which claim about scarcity is correct?Opportunity Cost
- How it worksHow do you identify the single next-best alternative you give up when you make a choice?
- Worked exampleFind the opportunity cost of spending 3 hours studying instead of working a shift that pays 15 dollars an hour.
- Common mistakeWhy isn't opportunity cost just the amount of money you hand over for something?
- Going furtherWhat happens to the opportunity cost of an activity when a much better alternative suddenly appears?
Your turn1 of 2
Find the opportunity cost of spending 6 hours studying instead of working a shift that pays 19 dollars an hour.Marginal Thinking: Costs and Benefits
- How it worksHow do you weigh the extra benefit of one more unit against the extra cost of producing it?
- Worked exampleFind whether to study a fifth hour when it raises your score by 2 points but costs 20 dollars in lost wages.
- Common mistakeWhy isn't the right choice found by comparing total benefit to total cost instead of marginal amounts?
Your turn1 of 2
Studying an additional hour raises your exam score enough to be worth 31 dollars to you, and costs 24 dollars in lost wages from skipping a shift. What is the net marginal benefit of studying that hour?Incentives and How People Respond to Them
- How it worksHow does raising the reward or lowering the cost of an action change how often people choose it?
- How it worksWalk me through how a bounty on rats backfired when people started breeding rats to collect the reward.
- Going furtherWhat happens when a policy changes an incentive for one group but ignores how a related group reacts?
- Ties togetherHow does the idea that people respond to incentives show up later as the slope of a supply curve?
Your turn1 of 2
A city pays residents five dollars for every rat tail turned in to reduce the rat population, but ignores that some residents could begin breeding rats to collect the bounty. What is the most likely result of this incentive design?The Circular Flow Diagram
- How it worksHow do goods and services flow from firms to households while money flows the opposite way in the product market?
- How it worksWalk me through how labor and other resources flow from households to firms in the factor market.
- Going furtherWhat happens to the circular flow when households suddenly save more of their income instead of spending it?
Your turn1 of 2
A household earns 5393 dollars this month, pays 460 dollars in taxes, and spends 2432 dollars on goods and services. How much does it save?The Production Possibilities Frontier
- How it worksHow do you draw a production possibilities frontier from a table of maximum outputs for two goods?
- Worked exampleFind whether 60 tons of wheat and 30 cars is inside, on, or outside a frontier where wheat = 100 minus 2 times cars.
- Going furtherWhat happens to the combinations available on a production possibilities frontier if a factory burns down?
Your turn1 of 2
A farm's production possibilities frontier is wheat = 135 minus 2 times cars, where wheat and cars are tons produced. If the farm currently produces 24 cars, what is the maximum tons of wheat it could still produce on the frontier?The Bowed-Out Shape of the PPC
- How it worksHow does moving resources that are bad at growing wheat into wheat production first explain the frontier's curve?
- Worked exampleFind the extra cloth given up to gain the next 5 units of wheat when the frontier goes from 40 wheat and 60 cloth to 45 wheat and 50 cloth.
- Going furtherWhat happens to the opportunity cost of wheat as a country keeps specializing further into growing more of it?
- Common mistakeWhy isn't the opportunity cost the same for every unit along a bowed-out production possibilities frontier?
Your turn1 of 2
A country's production possibilities frontier moves from 44 tons of wheat and 74 yards of cloth to 68 tons of wheat and 36 yards of cloth. What is the opportunity cost of one more ton of wheat, in yards of cloth, over this move?Shifts in the PPC and Economic Growth
- How it worksHow does discovering a new resource or a better technology push the entire production possibilities frontier outward?
- How it worksWalk me through why moving along an unchanged frontier is different from the whole frontier shifting outward.
- Ties togetherHow does investment flowing through the circular flow diagram end up shifting a country's production frontier outward?
Your turn1 of 2
New capital investment raises a country's corn-only production intercept from 68 tons to 135 tons, with the other intercept unchanged. By what percent did the corn intercept grow?Absolute Advantage
- How it worksHow do you compare two producers' output per hour to find who holds the absolute advantage in a good?
- Worked exampleFind who has the absolute advantage in coffee when one worker makes 4 pounds an hour and another makes 6 pounds an hour.
- Common mistakeWhy doesn't having the absolute advantage in a good decide which country should specialize in producing it?
Your turn1 of 2
Worker A produces 8 pounds of coffee per hour, and Worker B produces 3 pounds per hour. How many more pounds per hour does Worker A produce than Worker B?Comparative Advantage
- How it worksHow do you find comparative advantage by comparing each producer's opportunity cost instead of their output?
- Worked exampleFind who has the lower opportunity cost of coffee when A makes 4 pounds of coffee or 8 yards of cloth an hour, and B makes 6 pounds or 9 yards.
- Common mistakeWhy doesn't producing more of a good per hour automatically mean you have the comparative advantage in it?
- Ties togetherHow does comparative advantage give a different answer than absolute advantage about who should produce which good?
Your turn1 of 2
A worker can produce 5 pounds of coffee or 10 yards of cloth in an hour, devoting all her time to one or the other. What is her opportunity cost of one pound of coffee, in yards of cloth?Specialization and the Gains from Trade
- How it worksHow does trading at a price between both producers' opportunity costs make both sides better off?
- Worked exampleFind the gain from trading 4 pounds of coffee for 7 yards of cloth when A's cost is 2 yards per pound and B's cost is 1.5 yards per pound.
- Going furtherWhat happens to each country's consumption possibilities once they specialize and trade instead of producing everything themselves?
- Ties togetherHow does trading beyond your own production possibilities frontier let you consume at a point the frontier alone could never reach?
Your turn1 of 2
Country A's opportunity cost of one pound of coffee is 2 yards of cloth. It trades coffee to Country B at an agreed rate of 3.47 yards of cloth per pound, selling 10 pounds. How many yards of cloth beyond what producing that coffee itself cost Country A does it gain from the trade?Terms of Trade
- How it worksHow do you find the range of exchange rates where both trading partners come out ahead?
- Worked exampleFind the range of exchange rates for wheat and cloth when one country's cost is 2 bushels of wheat per yard and the other's is 4 bushels per yard.
- Going furtherWhat happens to the range of acceptable terms of trade when one country's opportunity cost changes over time?
Your turn1 of 2
One country's opportunity cost of one yard of cloth is 2 bushels of wheat, and the other's is 4 bushels. What is the midpoint of the two countries' opportunity costs, a terms of trade both sides could accept?