Just how long can it take to get ready to go to the fair? Some stories need to be set to music. The plot of this picture book is simple enough: A boy wants to go to the fair, but his family isn’t ready. There are pies to be baked and animals to be brushed. But this book’s really all about the rhymes. Many classic children’s books have succeeded entirely on a bouncy rhythm and a handful of clever rhymes, but the words here don’t bounce. The scansion seems, just faintly, wrong: “Hurry, Mama! Please, let’s go! / Let’s go to Derry Fair! / I want to ride the giant swing / That flies high / in the air!” A clever musician, with a little time, could make them catchy. For readers without time or the ability to improvise tunes, the real joy is in Tyler’s hide-and-seek illustrations. The watercolor-and-ink images are rendered in muted greens and browns, like spring, and they contain every toy or pet a preschooler might want. Children reading the book on their parents’ laps will search each page and say, “There’s a sheep! There’s a duck! There’s a hot-air balloon!” Even the homely interiors and details will fascinate. These pictures are more likely to stick in their heads than any of the couplets. (Picture book. 3-7)