Lesson preview · Economic Foundations
Scarcity & Opportunity Cost
~8 min · Free to read
You wake up Saturday morning with 50 dollars and 12 free hours. You could sleep in, go to brunch, see a movie, buy a new game, work a shift for extra cash, study for Monday’s exam — all at once? No. You have to choose. Try it for yourself:
That feeling — wanting more than you can have — is the starting point of all economics. Notice what just happened: every activity you tapped meant another one didn’t make the cut. The thing you DIDN’T pick is the real cost of what you DID pick. Economists have a name for both halves of this.
Key Term
Scarcity
The fundamental economic problem: human wants are unlimited, but the resources to satisfy them are limited. Even billionaires face it — a 90-year-old with 10 billion dollars can’t buy another year of youth.
Key Term
Opportunity Cost (OC)
The value of the NEXT BEST alternative you give up when you make a choice. Not all alternatives — just the single best one you didn’t pick.
Scarcity and opportunity cost are two sides of the same coin. Scarcity is the constraint (you can’t have everything). Opportunity cost is what scarcity feels like when you choose — the alternative you couldn’t fit. Every economic decision lives at this intersection.
The core formula — only the single best foregone option counts.
Trap · Common Misconception
Not every alternative counts
Students often add up all the alternatives. Wrong — opportunity cost is only the SINGLE best option you forgo. If you skip a party to study and you also skipped the gym, the OC isn’t both — it’s whichever you’d have enjoyed most.
Trap · Warning
Sunk costs are NOT opportunity costs
Money already spent and unrecoverable is a sunk cost — irrelevant to your next decision. If you bought a 100-dollar concert ticket that’s non-refundable, the 100 dollars is gone whether you go or not. The opportunity cost of going is just whatever else you’d do that night, not the ticket price.
Check yourself · no marks
You have 3 hours free. You could play video games (which you’d enjoy an 8/10), study (6/10), or go for a run (4/10). You pick video games. What is the opportunity cost?
Commit to one first. Guessing and being wrong beats reading the answer cold.
Worked Example
Lena has three options for her Saturday: work a 120-dollar shift at the bookstore, attend a free concert she’d really enjoy, or stay home and binge-watch Netflix (which she values at 20 dollars worth of enjoyment). She decides to go to the concert. What is her opportunity cost?
Tip
Micro vs Macro — a quick orientation
Microeconomics studies individual decision-makers (one consumer, one firm, one market). Macroeconomics studies the whole economy (GDP, unemployment, inflation). This course is microeconomics — the building blocks.
Practice · 1 / 5
Which situation best illustrates the concept of scarcity?
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