The case in three lines. A well-loved coach proposes a team rule: shout after bad games, never praise after good ones, because every time he did, the next game went the other way. Kiran says "after" is not "because", Sofia writes all twelve scores on the board and shows the pattern would appear on its own, and Yara proposes a coin toss. The coach asks Tara what she thinks, and the case stops there.

One question to ask. "What did Tara say?" Then: "Is there anything the coach is right about?" There is: praise and pressure can matter. The case is about how you would ever find out.

One thing to do at the table. Roll two dice twenty times and write down each total. Circle the three highest and the three lowest. What came after each? Nobody shouted at the dice.

The grown-up layer. Regression to the mean: when part of a result is chance, an extreme result tends to be followed by a less extreme one. Anyone who acts after extremes (a coach after a bad game, a parent after a bad report, a manager after a bad quarter) will see things "improve" after criticism and "slip" after praise, whether or not the criticism or praise did anything. Kahneman's flight-instructor story is the classic example. The only clean way to tell is a randomised comparison, which is why Yara's coin is the hero of the case.

The case leaves Tara's sentence blank on purpose. Ask for it before you offer yours.