A Drop of Water (by Walter Wick)

Take a breath -- you can almost fall into the photographs. This is a book to be digested rather than devoured, and everything about it tells the reader, "Go slow." It doesn't need to be read in one sitting, either; it can be picked up and leafed through until one of the photographs inevitably grabs the reader. More vivid and detailed than what can be seen with the naked eye, the pictures are so appealing, and the experiments so easy, that most children will be eager to try them out right away, with satisfying results.