World Economy · Learn with evidence
Trace a transport disruption through costs, retail prices and household choices, with a fictional cost exercise.
Free guided activity · 35 minutes · Ages 13 and up
Before you start: Percentages and the idea of a supply curve.
Learning goal: Explain a possible cost transmission channel without treating a freight-rate change as a retail-price forecast.
Preparation: Paper, pencil and calculator. Allow one shared screen for the linked tool, or use the printed exercise offline. Fictional figures are for practice.
A longer voyage can require more fuel, crew time and insurance. Delays can also affect storage and spoilage. Imported food can be exposed directly; domestic food may use imported fertilizer, packaging or fuel. Exposure differs by product and route.
Explore goods and trading partners →Freight is only part of a product’s cost. Contracts, inventories, alternative suppliers and competition affect whether and when a higher cost reaches shoppers. UNCTAD’s 2024 shipping reports provide a historical example of these channels; they are not a live forecast for the story you are reading.
Model a change in production costs →Choose a globe report and open the original source. Record its date, affected route and products, whether shipments actually changed, and whether a quoted number measures freight, wholesale costs or retail prices. Label missing information as unknown. Do not assume every country or grocery item is affected equally.
Choose a current report →Fictional importer: one shipment contains 1,000 identical food packages. Freight rises from $500 to $800 per shipment. Each package previously retailed for $4. Assume no spoilage or other cost changes for this exercise.
How much did freight rise per package, and by what percentage overall?
If the seller passes through exactly the extra cost, what is the new retail price?
What could reduce or delay that price effect?
Exit ticket: Explain one result in your own words and name an assumption that could change it.
Try the worksheet first. These answers explain the reasoning, not just the result.
The shipment costs $300 more, or $0.30 per package. Freight rose 60%: 300 ÷ 500 × 100.
$4.30, a 7.5% increase. A 60% freight increase is not a 60% retail increase. Exact pass-through is an exercise assumption, not a prediction.
Existing stocks, a fixed-price shipping contract, a shorter alternative route, or a seller accepting a smaller margin. Evidence is needed to determine which applies.
Next week: pick a different imported product and identify which costs would need checking before predicting a price change.
For a younger learner, work through the first calculation together. For an extension, change one assumption and defend the new conclusion.
See the related optional paid teaching pack →The complete activity above is free. The linked pack is a separate resource; this activity does not change its contents.
World Economy’s original exercises apply the concepts in these sources. Reviewed September 13, 2026. This is educational background, not a live event report.