Teach it. Check it. Revisit it.

Teacher guide

Audience: 12–18. Session: 30 minutes. Preparation: 5 minutes: paper and a calculator.

Prerequisites: Divide totals by population and calculate percentage changes.

1. Spend 5 minutes asking learners to predict the result and explain their reasoning.
2. Use most of the session for the student activity. Ask learners to show calculations and name assumptions.
3. Reserve 5 minutes for the exit questions. Discuss why the answer follows, not just whether it matches.
4. Return to the follow-up next week without showing today’s answers first.

Student activity

A fictional economy produces $1,000 of output for 100 people, then $1,100 for 110 people. Assume constant prices. Compare total output and output per person.

Write your prediction, calculation, explanation and one assumption you would check in a real situation.

Exit quiz

1. How much did total output grow?
2. Did output per person rise, and does it measure everyone’s wellbeing?

Teacher answers and reasoning

1. 10%: ($1,100 − $1,000) / $1,000.
2. No: both years have $10 per person. Even rising averages do not reveal distribution, unpaid work or environmental costs.

For each response, check the method, the result and the explanation. A correct number with an incorrect explanation needs another example.

Next-week review

Next week, change the second population to 105 and explain why total growth and per-person growth differ.

Facts, assumptions and policy debate

GDP is a defined measure of production. Deciding which aspects of wellbeing matter requires additional measures and explicit priorities.

Ask: what is calculated, what is assumed, and what is a judgment about priorities?