The Magic of Reality: How We Know What's Really True by Richard Dawkins (2011, Free Press). Dawkins, of course, is probably better known for his outspoken atheism and skepticism than he is for his scientific work as an evolutionary biologist and former professor at Oxford University.
The subtitle "How We Know What's Really True" best expresses the aim of this book. Dawkins begins the book with a discussion of the difference between reality and magic (the supernatural) and comes down, not surprisingly, on the side of naturalism - science is the only valid way to examine and learn about the natural world. As such, it's a very good introduction to how science operates and works but will obviously trouble those who would argue that there's more to the physical world since he doesn't shy away from including mainstream religion with other false ideas.
Throughout the book, Dawkins introduces a scientific question - Where did people come from? Why are there seasons? How do rainbows form? What causes earthquakes? - and then gives some culture's mythological explanation for the phenomenon (sometimes, the mythological explanation he provides is from the Bible). This is followed by the scientific explanation of the phenonomon showing, of course, how it's far more reasonable and useful than the myths.
While the book is described as for being of people of all ages, it's really written more like a book aimed for children. That's not to say adults would not get something from this book since most adults have no freaking idea why the Earth experiences seasons or how evolution works, but it does have the tone of a book for children. Given the vocabulary used and concepts discussed, the ideal age group for this book would probably be bright tweens. Assuming, of course, Dawkins saying stories about Adam and Eve in the Garden of Eden are myths on par with Quetzlcoatl, Zeus, and Ganesha doesn't offend you.
The thing I liked best about this book are the awesome illustrations on every page by Dave McKean. It would be worth getting the book just for these. Here are some examples (grabbed from the Amazon page for the book) below: