Shirley starts out the book as a Chinese girl who is excited to go to America, though she doesn't know anything about the country. She struggles to acclimate, but by the end of the story, she's presenting the key to P.S. 8 to her hero, the all-American star of her new favorite sport—and importantly, America's pastime—baseball superstar Jackie Robinson. Shirley's up on stage in front of her family, friends, classmates, and teachers, an audience that blends people from both her old and new worlds. Shirley, it seems, is officially Chinese-American at this point.
There's also a hint at a promising future for Shirley and her family since her mother is pregnant; Shirley insists the baby must be a boy. When Jackie Robinson tells Shirley she might be president one day, Shirley demonstrates her knowledge of her adopted country by telling him she can't be, if only because she wasn't born in the U.S.A. But her baby brother might be, since he will have been born in this country.
Shirley's brother will be the first member of Shirley's family to be born in America, and as such to be born an American citizen, but he'll have a big sister to teach him all about both of his cultural homes, one who knows all the cool stuff American kids should know and also all the cool stuff Chinese kids should know. The Wong clan is no longer just Chinese—they're a Chinese-American family.