First of, in the beginning of the book, Brent was a kid just worried about fitting in, and over the course of the book, those menial things don't matter to him anymore. Its like he has grown up and become more mature. For example, his interests towards the beginning where cars, sports, girls. But in the end of the book, he was more interested in reading, star gazing, and playing the harmonica, these activities are more for the adult crowd you’d think. So this just proves that people can change.
Second, In the chapter San Diego, with the holocaust survivor, She went through hell. Literally, like the quote says “I don't know who, said that there should be no laughing after Auschwitz. That nobody could ever want to laugh again after the things that happened here” (pg 113) So she thought she would never feel happiness or laugh again. But when her granddaughter took her around town, and she saw the whirligig, she changed. Like the quote says “ I glimpsed a smile on my grandmother's face, and I felt it leed” (pg 114). Again proving that people can change, no matter what happened in their past.
In all, when you think about it, people can change. No matter what they’ve done, no matter their past. Like with Brent, he was a typical teenager, but in the end, he was acting like a full fledged adult. And the Grandmother in the chapter “San Diego”, she was an elderly holocaust survivor, and she saw unimaginable things. She thought she would never feel happiness again. But the whirligig made he see the good thing in life, and she too, changed.