It's very interesting to imagine that in this book the children on Earth are organized into how old they are. There are loud speakers that announce important announcements throughout the city and in the end you find out that the main character is starting to have the ability to see in color.
My daughter read this book in school and would tell me about it as she read. I hated everything my daughter told me about it. If the teacher hadn't assigned it, I don't think my daughter would have read it either.