Teach & case
Help a near-peer reason through the idea — when you explain it, you understand it best — then read the real decision it comes from.
Help Elena read the game
What you've shown you can teach
A real case · you decide
Elena and the two food trucks in a price war
Elena — a student modeling two rival food trucks that both keep cutting prices until neither will move
Two food trucks share a corner. Each keeps undercutting the other until both sit at rock-bottom prices, each barely breaking even. Neither will raise first. Elena's friend says "well, that's the equilibrium, so it must be the best they can do." Is it?
At the low-low prices, if either truck alone raises its price, it loses all its customers to the rival — so neither wants to move. That's what "equilibrium" means: no player gains by unilaterally switching. It's STABLE.
But both-keep-prices-high would earn each of them MORE. It's better for both — yet it isn't an equilibrium, because from there either truck gains by secretly undercutting. Stable and best-for-both are different questions.
Both trucks are at rock-bottom prices, neither willing to move. Is this the best outcome they could reach?
Elena says "the high-price outcome is better for both, so THAT must be the real equilibrium." Does better-for-both make it an equilibrium?
Elena's habit is to ask the two questions separately: is this stable (can anyone gain by moving alone?), and is this good (could everyone do better?). Confusing the two is how a race to the bottom gets mistaken for the best anyone could hope for.