Classroom · Game Theory
Two plans, one evening, and no right answer to coordinate on.
You would both rather be together at the other's thing than alone at your own — so there are two ways tonight works, you each prefer a different one, and politely deferring fails exactly as badly as digging in. Played in pairs, twice, the second round final.
- In pairs
- About 30 min
- 2 acts
A practice run with fictional students. No real classroom or join code is created.
Try an answer on the phone. Lead the lesson from the screen.
On their phone
You are presenting
Setting up the room…
Lesson deck
Teach it as a ready-made lesson
Hook, how it works, the live game and takeaways. Edit anything.
One evening, two plans
A ready-to-teach lesson deck: a hook, how it works, the live game and takeaways for the debrief.
6 slides · 1 activity
What it teaches
This is the coordination game where the players' interests mostly align and still manage to conflict: both equilibria are good, the two sides rank them oppositely, and there is no principled way to choose. Students learn why coordination problems are not solved by goodwill — a pair of players each generously deferring miscoordinates just as surely as a pair each insisting — and why conventions, commitments and even arbitrary signals earn their keep.
- Coordination problems
- Nash equilibrium
Debrief, while the boards are still up
- 01
Both of you deferring failed. Both of you insisting failed. What would have actually worked?
- 02
If one of you could have sent a single message first, what should it have said — and would it have been fair?
- 03
What conventions do we use outside this room to break exactly this kind of tie?
How it works
- 01
Add it to your library
Sign up free and pull the activity from Decka's built-in classroom catalog — one click copies it into your own library, ready to run from Decka or inside PowerPoint.
- 02
Students join by QR
Everyone scans from the projector and plays in their phone's browser. No app, no account, nothing to install.
- 03
You run the room
You move the activity phase by phase: collection closes, the boards resolve on the big screen, and the debrief happens while the results are still up.
What is the battle of the sexes in game theory?
The battle of the sexes is game theory's standard example of coordination with conflicting preferences: one free evening, two plans, no way to reach each other before setting off, and a payoff table where being together at either event beats being apart at both. It has two pure equilibria — one per plan — and each player prefers a different one. The name is a period piece; the structure is everywhere: two firms picking a technical standard, two departments picking a meeting time, two countries picking a treaty venue.
Playing it live is the fastest way to teach why "just be reasonable" is not a strategy. The activity strips the game to its symmetric core — hold out for your plan, or give in to theirs — so a pair of students who both give in discover they have coordinated on nothing, exactly as if they had both dug in. By the second round, which the scenario makes final, the room is inventing conventions on its own: alternation, deference to whoever spoke first, a coin flip. That invention is the lesson — equilibrium selection is a social technology, and your class just built one.
FAQ
Battle of the sexes questions, answered
Why 'hold out' and 'give in' instead of naming the two plans?
The activity plays the game in its symmetric form: each student chooses whether to insist on their own plan or defer to their partner's. The structure — two equilibria, ranked oppositely — is identical, and the symmetric framing means every pair plays the same board and the room's results can share one matrix.
Is this the same as the chicken game?
They are related — both have two lopsided equilibria and no dominant strategy — but in chicken the miscoordinated crash is the worst cell on the board, while here the disagreeable outcomes are simply being apart. Chicken is a game about disaster; this is a game about compromise, which is why its politics feel so familiar.
How long does it take?
Two short rounds; the saved default shows under the headline as "About N min", and all timing is adjustable before you run it.
Do students need an app or an account?
No. Students scan a QR code from the projector (or open a link) and play in their phone's browser. Nothing to install and nothing to sign up for.
Does it work in PowerPoint or Google Slides?
In PowerPoint, yes: open the Decka add-in on a slide and choose the Classroom tile. Google Slides is not supported yet; there you present from Decka itself. Students play from their phones either way.
How many students can play at once?
Up to 50 participants per live activity on the free plan, 150 on Pro, and 300 on Badass.
More game theory games to run live
- Prisoner's dilemma — two suspects, separate rooms
- Twenty coins, take it or leave it
- Chicken — four seconds on a single-track lane
- The stag hunt — one day, two ways to spend it
- Ten rounds in the pot
- Rock, paper, scissors — two rivals and a contract
- Matching pennies — the game where you want opposite things
- All game theory activities
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