Let’s Do Classwork! is a free collection of interactive economics exercises. I built them from the problem sets I use in my applied microeconomics courses at Missouri University of Science and Technology. Each lab lets students change inputs, see the result right away, and check their answers. The labs cover supply and demand, marginal analysis, elasticity, cost curves, game theory, market power, environmental economics, and U.S. pollution abatement cost data. Undergraduates, graduate students, and self-learners can use them to review a concept before an exam or to prepare for graduate coursework.
At a glance: 11 free interactive labs (seven microeconomics labs plus a four-part environmental economics lab)
· Levels: undergraduate, graduate, and general audience
· Created by Mahelet G. Fikru, Professor of Economics, Missouri S&T
· Last updated September 2026.
Find a lab by level
Undergraduate review: The Efficiency Lab
Graduate review: the Equilibrium, Nash, Elasticity, Cost, and Market Power Labs
No economics background needed: The Workforce Lab
Environmental and resource economics: The Environmental Economist Lab
1. The Equilibrium Lab: Supply and Demand, Profit Maximization, and Risk
This interactive exercise covers three fundamental economic concepts in one handout: shifting a market to see how supply and demand respond to changing conditions, chasing a profit-maximizing output level to find where a firm should produce, and pricing two risky investments to compare returns against risk. Click through each one, adjust the inputs, and see the concept play out in real time instead of just reading about it.
Concepts covered: market equilibrium, shifts in supply and demand, profit-maximizing output, expected return and risk.
Recommended for graduate students who need to review concepts in microeconomics.
2. The Nash Lab: Game Theory and the Principal–Agent Problem
This interactive exercise covers the agency problem between managers and owners — why managers acting on shareholders' behalf don't always choose what's best for the firm, and how strengthening monitoring changes the payoffs enough to shift the equilibrium outcome.
Concepts covered: Nash equilibrium, payoff matrices, the principal–agent problem, monitoring and incentives.
Recommended for graduate students who need to review concepts in game theory.
3. The Efficiency Lab: Marginal Analysis, Consumer and Producer Surplus, and Taxes
This interactive exercise covers the efficiency of markets — finding the optimal input level where marginal benefit meets marginal cost, deriving market equilibrium from supply and demand, and measuring the net benefits a market creates through consumer and producer surplus, including how a per-unit tax changes that split.
Concepts covered: marginal benefit and marginal cost, market equilibrium, consumer surplus, producer surplus, tax incidence.
Recommended for undergraduate students who need to review marginal analysis and market surplus.
4. The Workforce Lab: Data Center and Computing Jobs (NAICS 518)
An interactive look at who works in Sector 518 (computing infrastructure, data processing, hosting, and related services) and how that's shifted over time. Explore employment broken down by sex and by education level from 2010 to 2025, including a widening gender gap. Since data center jobs fall within this sector, tracking Sector 518 is one of the few ways to see AI-driven data center employment show up in the numbers, even though it isn't broken out on its own.
Concepts covered: employment trends, the gender gap in tech employment, education levels, how AI and data center jobs show up in industry data.
Data: U.S. Census Bureau, LEHD Quarterly Workforce Indicators (QWI).
Recommended for anyone with no formal training on economics or data analysis.
5. The Elasticity Lab: Price, Cross-Price, and Income Elasticity of Demand
This interactive exercise covers price, cross-price, and income elasticity of demand — calculating and interpreting each measure, along with how elasticity connects to total revenue (TR) and marginal revenue (MR).
Concepts covered: price elasticity, cross-price elasticity, income elasticity, total revenue, marginal revenue.
Recommended for graduate students in applied microeconomics who have a good command of analytical skills and a solid understanding of the demand-supply model.
6. The Cost Lab: Short-Run and Long-Run Cost Curves
This interactive exercise covers the structure of short-run production costs, deriving the relationships between total, fixed, and variable costs; using marginal cost to find how the cost of the next unit changes, and distinguishing accounting profit from economic profit through an opportunity-cost decision, including a look at how the long-run cost curve differs from the short-run one.
Concepts covered: total, fixed, and variable cost; marginal cost; opportunity cost; economic vs. accounting profit; long-run average cost.
Recommended for graduate students who need to review cost curve relationships and the accounting-vs-economic-profit distinction.
7. The Market Power Lab: From Perfect Competition to Monopoly
This interactive lab walks students from perfect competition to monopoly through guided stations. Students derive equilibria, fill in calculation tables, build an Excel model, and get instant feedback as they go.
Concepts covered: perfect competition, monopoly pricing, deadweight loss, building the model in Excel.
It is recommended for graduate applied microeconomics as a hands-on refresher on imperfect competition.
8. The Environmental Economist Lab
A steel mill pollutes the air and never pays for the damage. Solve the competitive and efficient equilibria, add marginal damage cost to get marginal social cost, and measure the deadweight loss of a negative externality.
Public goods and common-pool resources side by side: a climate abatement game between two emitting blocs, a shared wetland buffer solved with the Samuelson condition, and a groundwater aquifer facing the tragedy of the commons. Shows why the free-rider problem and the tragedy of the commons come from the same root: non-excludability.
C. Nuclear Generation in the US
Who works in U.S. nuclear power plants (NAICS 221113), by state and by sex, quarter by quarter from 2007 to 2025. Data: U.S. Census Bureau, LEHD Quarterly Workforce Indicators.
D. Abatement Cost Atlas: U.S. Manufacturing Pollution Abatement Costs by State and Industry (2005)
How much did U.S. manufacturers spend to reduce pollution, and where did that money go? In 2005, plants spent about $20.7 billion on pollution abatement operating costs and $5.9 billion on abatement equipment. This interactive atlas turns the raw Excel tables from the Pollution Abatement Costs and Expenditures (PACE) survey into a map and filterable charts. Compare spending by state and manufacturing sector, and break it down by activity (treatment, prevention, recycling, disposal), by media (air, water, solid waste), and by cost category (labor, energy, materials, contract work, depreciation). Data: U.S. Census Bureau, PACE 2005 survey.
More coming soon
This is the start of a series. More classroom exercises will turn into these interactive pieces and land here as they’re made. Try them out, and share what’s confusing, what’s fun, and what you’d want to see documented next. I built these labs with the help of AI tools, as part of the broader shift I describe in AI in higher education: What institutions should do next.
Check back here again for more updates.
Frequently asked questions
What is Let’s Do Classwork?
Let’s Do Classwork! is a free set of interactive economics labs created by Mahelet G. Fikru, Professor at Missouri University of Science and Technology. It currently includes seven microeconomics labs and a four-part Environmental Economist Lab, each built from exercises she uses in her own courses.
Are these economics exercises free?
Yes. Every lab is free to use, with no sign-up required.
Where can I practice supply and demand problems online?
The Equilibrium Lab and the Efficiency Lab let you shift supply and demand, solve for equilibrium price and quantity, and calculate consumer surplus, producer surplus, and the effect of a per-unit tax, with instant feedback.
How do you calculate the deadweight loss of a negative externality?
Find the efficient quantity where marginal benefit equals marginal social cost (private cost plus marginal damage). The deadweight loss is the triangle between marginal social cost and demand, from the efficient quantity out to the competitive quantity. The Externalities lab walks through a full worked example.
What is the difference between the free-rider problem and the tragedy of the commons?
Both come from non-excludability. With a public good, people contribute too little, so it is under-provided. With a common-pool resource, people use too much, so it is run down. The Commons Lab works through both.
How much do U.S. manufacturers spend on pollution abatement?
In 2005, U.S. manufacturing plants with 20 or more employees spent about $20.7 billion on pollution abatement operating costs and $5.9 billion on abatement capital expenditures, according to the U.S. Census Bureau’s Pollution Abatement Costs and Expenditures (PACE) survey. Chemical manufacturing had the highest operating costs ($5.2 billion), followed by petroleum and coal products and primary metals. Texas, California, and Louisiana spent the most among states. The Abatement Cost Atlas breaks these figures down by state, sector, activity, and media.
Who are the labs for?
Each lab is labeled by level. Most target graduate applied microeconomics, the Efficiency Lab targets undergraduates, and the Workforce Lab needs no economics background.
Can instructors use these labs in class?
Yes. Instructors can link to any lab from a syllabus or learning management system. Feedback on how you use them is welcome in the comments.
How often are new labs added?
New labs are added as more classroom exercises are converted into interactive versions. Subscribe to get each new lab when it is published.
About the author
Mahelet G. Fikru is a Professor at Missouri University of Science and Technology, where she teaches applied microeconomics courses. Her research covers energy transition economics, critical minerals, and public policy. She writes M G Fikru, a newsletter on energy, natural resources, technology, and sustainability.
Sooo cool! I can't wait to see what the students make of them!