The truth that one small act of kindness does in fact change the world is beautifully expressed in this story. Yes, it is sweet and simple but it also goes to a new level showing, with exponential growth how one kind gesture from one person to another really can impact six billion people. My grade 5-6 kids were touched by the sweetness of the story and the illustrations but were genuinely excited and moved by the mathematical "proof" that this isn't just a nice idea. I discovered this book at a math workshop, actually. Don't hesitate to buy it. What a gem!