Key to success

Pia holds up one of her drawings:

Pia: The first one to raise their hand will get this drawing.

Daddy raises his hand first.  Pia gives the drawing to Mummy.

Daddy: Hey, I raised my hand first. Why did you give the drawing to Mummy?

Pia: (gives complicated explanation why, and then...) Tomorrow if you want to get the drawing you must be faster -- you must try harder than your best.

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