Thanks to a memorable marriage of impressive technology and seemingly hand-crafted storytelling, the well-worn piggy tale impresses at every page turn. Using an extremely wide range of tricks, from line drawings and interactive full-color illustrations to objects seemingly held up and drawn back into place by pieces of colored yarn, the app nearly overreaches in its ambition but pulls back just enough to succeed admirably. Movable tabs similar to those in traditional pop-up books pivot characters and create action within Brooke's classic 1904 illustrations. But the real showstopper is a unique X-ray feature. Present on most pages that have interactive elements, clicking the X-ray–glasses icon reveals the hidden springs, levers and pulleys that would seemingly cause the movement on the screen. It's a surprising, extremely effective extra that coexists nicely with the well-paced text and an interface that utilizes realistic-looking buttons (the kind held onto clothing with thread). If there's one thing to squeal about amid such nice design work, it's that the first two pigs and the wolf meet grisly ends that are typically toned down in some modern versions of the story. Save it for older kids, who will love seeing how the movable parts work. (iPad storybook app. 5-12)
