I bring candy to class. Chocolates, Starbursts, Hershey’s Kisses. I don’t explain why. I just put them on the table and tell students they’re going to eat some.

The first piece always goes fast. The second too. By the third or fourth, you can see it — the hesitation, the “I’m good actually.” Nobody has said the words diminishing marginal utility yet, but every student in the room has just experienced it.

That gap between the first piece and the fourth is the whole lesson. Utility isn’t some abstract satisfaction score. It’s the difference between lighting up when you unwrap the first Starburst and pushing the fourth one away. The marginal part is key — we’re not measuring total enjoyment, we’re measuring how much the next unit adds. And it adds less. Every time.

The candy also opens up a conversation about rational decision-making. Students stop eating when the next piece isn’t worth it anymore — when marginal utility falls below some internal threshold. They didn’t need a formula for that. They just did it. The economics just describes what they already know.

The production possibility frontier is one of the first real models students encounter. It’s also one that tends to die on the whiteboard — a neat curve with labeled axes that students dutifully copy and promptly forget.

The version I use starts with a question, not a diagram. I ask students: if this economy has to produce two things — guns and butter — what happens to butter production if we decide to build more guns? They usually get it immediately. The constraint is intuitive. But intuition and a model are different things, and this is where the activity earns its place.

I have students sketch their own frontiers before I draw one. They pick combinations, plot them, and start to see the shape emerge. The curve isn’t something I’m handing them — it’s something they’re constructing. Once it’s on the page, the questions get more interesting. What does a point inside the frontier mean? What does a point outside it mean? How do you get there?

From there, the conversation moves naturally to consumption and investment. A society that devotes more resources to investment today — machinery, infrastructure, education — can push the frontier outward over time. But that means producing less consumption now. The tradeoff is real. Students usually arrive at something close to capital accumulation on their own. You just have to ask the right questions and let them work it out.

I bring iced tea to class. Real iced tea. Two or three bottles, cold.

Before anyone sees them, I ask a simple question: what would you pay for an iced tea right now? I go around the room and record the answers on the board. No discussion yet — just numbers. Then I do the same thing with a twist: it’s a hot day in August. Same question. Then: it’s January and you just came in from the cold. Same question again.

The numbers move. A lot. Students who said fifty cents in January are suddenly at three dollars in August. Nobody taught them that. They just know it. And that’s the point — demand isn’t a fixed fact about a person. It shifts.

Then I pull out the actual iced tea. I tell them they can buy one if they want. I name a price. I watch who raises their hand and who doesn’t. That’s willingness to pay made visible. We build the demand curve together from the board numbers — rank them, plot them, and there it is.

I tell them at the end that I’m not actually taking any money. But the hands they raised were real.

This one ends badly. On purpose.

Students play fishermen. There’s a lake. The lake has fish — a fixed, regenerating stock. Each round, every student decides privately how many fish to catch. If total catches stay under the sustainable threshold, the stock recovers and the game continues. If they go over, the stock collapses. Game over.

Here’s what almost always happens: someone defects early. They take more than their share because the incentive is there — the fish are valuable, the lake belongs to everyone, and if you don’t catch them someone else will. Once others see that logic, they follow. The stock is usually gone by round three.

That’s the tragedy. Not that people are greedy. It’s that the structure makes rational individual behavior collectively irrational. No one decides to destroy the lake. They just respond to the incentives in front of them. The market failure isn’t a moral failure — it’s a design failure.

The debrief is where the real teaching happens. What could have prevented this? Students usually converge on some combination of quotas, privatization, or cooperative agreements. Those map onto the actual policy responses to common pool resource problems. Coase, Ostrom, Pigou — all of it connects cleanly after students have just watched themselves fail.

Most students have heard of ranked choice voting. Almost none of them understand why it matters.

This game starts with a policy menu. I either prepare three or four proposals in advance — things like free campus parking, extended library hours, a new student fee for sustainability — or I solicit them from the class on the spot. Both work. Soliciting from the class makes students more invested.

Then I introduce the voters. Some are real — the students themselves. Others are NPCs that I control: a fiscal conservative, a progressive, a centrist, someone who only cares about one issue. I give each NPC a visible preference profile, posted on the board. This is intentional. Part of the lesson is understanding that voting outcomes depend not just on what people prefer but on how preferences aggregate.

We run two elections: first-past-the-post, then ranked choice. The outcomes often differ. Sometimes dramatically. Students can see how the same set of preferences produces a different winner depending on the rules — which is the point. The median voter theorem explains a lot about why candidates converge. Ranked choice changes those incentives. Arrow’s impossibility theorem is waiting in the wings if you want to go further.

What I like about this game is that it’s genuinely surprising. Students come in thinking they already understand voting. They leave less sure, which is usually the right outcome.