It was getting late, and the mothers on the playground were beginning to shift on their feet. Conversation was lagging, and eventually one of the women waved to her son.
"C'mon birthday boy!" she called. "Time to go home!"
As the child jumped down from the monkey bars, landing in a group of guffawing classmates, another woman turned to her in surprise.
"It's his birthday? I didn't know it was...