Since its first publication in 1989, Martin and Ehlert's Chicka Chicka Boom Boom has delighted preschoolers with its rhyme about an irresistibly rowdy alphabet that scales a tree. Tree-climbing numbers replace letters in this follow-up, which is as visually exciting as the earlier book. Ehlert's cut-paper collages retain the previous title's tropical hues and solid, playful shapes, but the conceptual exercise is more challenging than in the first book, which simply ran, letter by letter, up and down the alphabet. Here the numbers ascend by ones up to 20, after which they switch to intervals of tens (30, 40, 50) until they reach 90, which is followed not by 100, but by 99. Zero follows 99, accompanied by text that may confuse children: "0 lands on top / of the tree, / joins with 10. / Now 100 you see!" Adults will probably need to explain the math; the bright endpapers that count by ones to 100 will help. Despite the tricky concepts, though, the chanting rhyme and eye-popping images have a contagious energy youngsters will find irresistible. Gillian Engberg Copyright © American Library Association. All rights reserved