Harris’s latest math-concept book (Splitting the Herd, 2008, etc.) expands “Hickory Dickory Dock” into a 12-hour romp throughout the farm. The mouse’s problem? Why, the cat, of course. “Hickory dickory doo, the grandfather clock struck TWO. / It woke the cat, who sprang from his mat, / hungry for mouse-tail stew.” And so the chase begins. Each turn of the page reveals that another hour has passed and another member has joined the pursuit. Readers can track the time on the diverse clocks—from cuckoo and grandfather to church tower and digital. Scanning well, this would work well for read-alouds, although the smallish trim size will limit the size of the group. Backmatter includes some facts about clocks and teaches children how to tell time by the hour on both digital and analog clocks. Hartman’s characters are full of personality—the cat is high-and-mighty while the dog is just plain loopy. Her colors reflect the passing of the day, getting increasingly darker as the sun disappears and the characters become sleepier. With its emphasis on the hours, this has great potential for the youngest audiences. (Picture book. 4-7)