Can both sides gain from trade?
If one team can make more bread, should it make everything?
Compare what each producer gives up to make one more unit. A lower opportunity cost identifies comparative advantage. Greater output from the same resources identifies absolute advantage. They answer different questions.
Try the fictional case
Elm and Pine each have one day of resources. Elm can make 12 loaves of bread or 6 blankets. Pine can make 6 loaves or 6 blankets. Each can divide the day between goods at a constant rate. Goods are divisible for calculation and identical in quality. There are no transport costs.
| One day of resources | Bread only | Blankets only |
|---|---|---|
| Elm | 12 loaves | 6 blankets |
| Pine | 6 loaves | 6 blankets |
- How many loaves does Elm give up to make one blanket? How many does Pine give up?
- Who has the comparative advantage in blankets? Who has it in bread?
A simple 20 minute plan
Spend 4 minutes on the opening question, 8 on the table and calculations, 5 comparing explanations, and 3 on an exit ticket: “My conclusion is ____. One assumption that matters is ____.”
Open teacher answers
- Elm gives up 12 / 6 = 2 loaves for one blanket. Pine gives up 6 / 6 = 1 loaf.
- Pine has the lower opportunity cost in blankets. Elm gives up 0.5 blanket per loaf, compared with Pine’s 1, so Elm has the comparative advantage in bread.
Absolute advantage does not determine comparative advantage. Trade can expand feasible consumption in a model without guaranteeing equal gains, painless adjustment, or benefits for every individual.
Teacher answer guide
- Elm gives up 12 / 6 = 2 loaves for one blanket. Pine gives up 6 / 6 = 1 loaf.
- Pine has the lower opportunity cost in blankets. Elm gives up 0.5 blanket per loaf, compared with Pine’s 1, so Elm has the comparative advantage in bread.
Absolute advantage does not determine comparative advantage. Trade can expand feasible consumption in a model without guaranteeing equal gains, painless adjustment, or benefits for every individual.
State the limit
This two-producer model omits adjustment costs, bargaining power, differences within each community, changing productivity, and preferences. Do not turn a calculated possibility into a claim about every real trade policy.
Further reading: OpenStax: absolute and comparative advantage. Activities and examples are original to World Economy. A reference does not imply endorsement.
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