“I’ll race you to the corner, Ellen!” Annemarie adjusted the thick leather pack on her back so that her school books balanced evenly. “Ready?” She looked at her best friend.

Ellen made a face. “No,” she said, laughing. “You know I can’t beat you-my legs aren’t as long. Can’t we just walk, like civilized people?” She was a stocky ten year-old, unlike lanky Annemarie.

“We have to practice for the athletic meet on Friday- I know I’m going to win the girls’ race this week. I was second last week, but I’ve been practicing every day. Come on, Ellen,” Annmarie pleaded, eyeing the distance to the next corner of the Copenhagen street. “Please?” Ellen hesitated, then nodded and shifted her own rucksack of books against her shoulders. “Oh, all right. Ready,” she said.

“Go!” shouted Annemarie, and the two girls were off, racing along the residential sidewalk. Annemarie’...