Teacher pilot kit · no account needed
Group-Chat Reputation: a 20-minute game-theory activity
Everything to run one useful lesson next class — a teacher guide, a projector view, a printable student sheet, an answer key, and a direct student link. Nothing to install; students never make an account.
Teacher guide
- Hook (2 min). Project the scenario below. Ask: "In a group chat, why do people usually keep their word even when breaking it would be easier right now?"
- Frame (3 min). Introduce the idea of a repeated game: you'll interact with these same people again, so today's move sets tomorrow's price. Reputation is the memory the group carries forward.
- Play (8 min). Run the interactive "Reputation Rounds" on the projector, taking a class vote each round, OR have students open it on phones via the link/QR below. After each round, read the consequence aloud.
- Debrief (5 min). Use the discussion questions. Draw out: a one-time win often costs future cooperation; repair is possible but slower than the original trust.
- Exit (2 min). Students complete the printable sheet or answer question 5 aloud: "Where in your real week is this a repeated game, not a one-shot?"
Facilitation notes: Keep it about the structure of choices, not about labeling real classmates. If a student shares something personal or distressing, pause and follow your school's support process — this is a lesson, not counseling.
Optional extension: Students play a full run of The Long Game (3 minutes) and report one scenario where reputation changed their answer.
Project this: the scenario
The situation
You're in a five-person group chat for a class project. You promised to post your part tonight. A friend invites you out — if you bail on the work, you get the fun now, but the group finds out you didn't deliver. You'll be working with these same four people for the rest of the term.
The question each round: keep your word, or take the quick win?
Reputation Rounds
Round 1 of 5 — the group's trust in you
Group trust: 60/100 · Your points: 0
Choose a move to see how the group responds.
Reputation Rounds — payoff table (fallback)
| Your move | Now | Next round |
|---|---|---|
| Keep your word | +2 points, trust +8 | Group shares work, easier |
| Take the quick win | +5 points, trust −25 | Group double-checks you, harder; repair is slow |
Printable student sheet
— the print version shows only the scenario, questions, and payoff table.
Name a situation, not a person.
- What felt most real about the group-chat scenario?
- When was taking the quick win most tempting? What made it tempting?
- After a broken promise, what does it actually take to rebuild trust?
- Describe one repeated game in your own week (same people, again and again).
- What rule would you give a new group to protect trust and allow repair?
Discussion & answer guide
- Q1 (real): Look for the pull between an immediate reward and a future cost — that tension is the whole lesson.
- Q2 (temptation): Best answers notice that the quick win is concrete and now; the cost is abstract and later. Present bias.
- Q3 (repair): Rebuilding takes consistent follow-through over several rounds — trust falls fast and rebuilds slowly. There's no single-move fix.
- Q4 (repeated game): Any recurring group — team, friends, family chores, a job. The point is recognizing "I'll see these people again."
- Q5 (rule): Strong rules make expectations explicit AND leave room for a mistake to be repaired (e.g., "tell the group early if you can't deliver").
Send students here
Point phones at the QR or share the link:
goodchoicesociety.org/game
No names, no class codes, no accounts.