Goods We Under-consume and Over-consumeActivities & Teaching Strategies
Active learning works for this topic because students often form opinions based on personal experience rather than economic reasoning. By engaging with real-world examples through discussion, debate, and role-play, students confront their assumptions and see how market failures shape behavior. This approach makes abstract concepts like externalities tangible and relevant to their lives.
Learning Objectives
- 1Analyze the divergence between private consumption choices and social welfare for merit and demerit goods.
- 2Evaluate the effectiveness of government policies such as subsidies and sin taxes in correcting market failures related to under- and over-consumption.
- 3Compare the economic rationale for government intervention in markets for goods with positive externalities versus negative externalities.
- 4Explain how imperfect information contributes to the under-consumption of merit goods.
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Think-Pair-Share: Classifying Goods
Students individually list five everyday goods and label them as merit, demerit, or neutral with reasons. In pairs, they compare lists, discuss externalities, and refine classifications. Pairs share one example with the class for a quick vote and explanation.
Prepare & details
Why might people not consume enough of things that are good for them, like healthy food or exercise?
Facilitation Tip: During Think-Pair-Share, circulate to listen for misconceptions about positive externalities in merit goods and correct them immediately in the sharing phase.
Setup: Standard classroom seating; students turn to a neighbor
Materials: Discussion prompt (projected or printed), Optional: recording sheet for pairs
Small Group Debate: Policy Interventions
Divide class into groups assigned to argue for or against subsidizing healthy food versus taxing gambling. Groups prepare evidence using diagrams and Singapore examples, then debate in a structured format with rebuttals. Conclude with a class vote on best policy.
Prepare & details
Why might people consume too much of things that are bad for them, like sugary drinks or gambling?
Facilitation Tip: For Small Group Debate, assign roles (e.g., policymaker, consumer, economist) to ensure all students contribute and engage with counterarguments.
Setup: Groups at tables with case materials
Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template
Diagram Stations: Externalities Shift
Set up stations with merit and demerit good scenarios. Groups draw initial and post-policy supply curves, label externalities, and calculate efficiency gains. Rotate stations, adding peer feedback before presenting one diagram to the class.
Prepare & details
How can the government encourage or discourage the consumption of certain goods?
Facilitation Tip: Set clear time limits at Diagram Stations to keep groups moving and prevent over-analysis of any single externality shift.
Setup: Groups at tables with case materials
Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template
Whole Class Simulation: Market Trading
Distribute cards representing merit and demerit goods with hidden externality values. Students trade in a mock market, then reveal externalities and adjust trades. Discuss how information asymmetry led to under- or over-consumption.
Prepare & details
Why might people not consume enough of things that are good for them, like healthy food or exercise?
Facilitation Tip: In Market Trading, start with simple goods before introducing demerit goods to build confidence, then gradually increase complexity.
Setup: Groups at tables with case materials
Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template
Teaching This Topic
Experienced teachers approach this topic by grounding economic theory in relatable examples, such as healthcare or sugary drinks, to show how imperfect information distorts decisions. They avoid lecturing on externalities without first letting students discover them through guided activities. Research suggests that peer teaching during debates or simulations helps students internalize the costs and benefits of under- and over-consumption more deeply than passive instruction.
What to Expect
Successful learning looks like students accurately classifying merit and demerit goods using externalities as the guide. They should explain why private decisions diverge from social welfare and evaluate policy interventions with evidence. Diagrams should reflect shifts in supply and demand that correct market failures, not just static curves.
These activities are a starting point. A full mission is the experience.
- Complete facilitation script with teacher dialogue
- Printable student materials, ready for class
- Differentiation strategies for every learner
Watch Out for These Misconceptions
Common MisconceptionDuring Think-Pair-Share, watch for students who assume that people always consume merit goods like education if they are available.
What to Teach Instead
Use the Think-Pair-Share to have students compare personal examples of education decisions with societal benefits, then re-examine their initial assumptions with diagrams showing positive externalities.
Common MisconceptionDuring Small Group Debate, watch for students who claim demerit goods only harm the consumer.
What to Teach Instead
Have groups tally the group-wide costs (e.g., healthcare, productivity) from over-consumption during the debate and use this data to adjust their supply and demand diagrams.
Common MisconceptionDuring Diagram Stations, watch for students who argue that any government intervention distorts markets.
What to Teach Instead
Ask groups to compare before-and-after diagrams to see how targeted taxes or subsidies internalize externalities, then discuss trade-offs in the debrief.
Assessment Ideas
After Think-Pair-Share, listen for students to connect imperfect information and opportunity costs to under-consumption of education, using peer examples to challenge initial assumptions.
During Diagram Stations, collect each group’s final diagram and justification for classification to check for accurate use of externalities in labeling merit and demerit goods.
After Whole Class Simulation, ask students to write one policy Singapore uses for a demerit good and explain how it corrects the market failure on their exit ticket.
Extensions & Scaffolding
- Challenge early finishers to design a new policy intervention for a market failure not covered in class and present it to the class.
- Scaffolding for struggling students: Provide partially completed diagrams with labels missing, or give sentence starters for debate arguments to reduce cognitive load.
- Deeper exploration: Ask students to research a real-world example of a merit or demerit good in another country and compare its policy response to Singapore’s approach.
Key Vocabulary
| Merit Good | A good that is under-consumed because individuals do not fully appreciate its benefits, leading to positive externalities and a divergence between private and social benefits. |
| Demerit Good | A good that is over-consumed because individuals do not fully appreciate its costs, leading to negative externalities and a divergence between private and social costs. |
| Positive Externality | A benefit that is enjoyed by a third party as a result of an economic transaction, such as the societal benefits of education or vaccination. |
| Negative Externality | A cost that is suffered by a third party as a result of an economic transaction, such as the health costs associated with smoking or pollution. |
| Sin Tax | An excise tax imposed on goods deemed harmful to society, such as tobacco, alcohol, or sugary drinks, intended to discourage consumption. |
Suggested Methodologies
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