This is one of a series of books designed to get children interested in science/nature. The others in the series are pretty good, but this, IMO, is fantastic. It's written in rhyme, which makes for a fast pace, with incredibly detailed cartoon pictures. Excellent for promoting discussion - for example, examples of walls that keep things out (with barbed wire etc) or in (a prison.... or a tin of beans). From 4 to 8ish. Would appeal to boys as well as girls. One of our favourites.