Franco plus Salerno add up to plenty of fun in this nimble brain teaser. Mixing math and language as she frolics through the four seasons, Franco (Counting Caterpillars and Other Math Poems) plucks equations from scenarios familiar to her audience, from Halloween ("pumpkin – seeds + face = jack-o'-lantern") to snowy days ("1/2 of icicle = ice") to summer vacation ("rocks × waves = sand"). There are graphs and fractions, angles and arcs, and through it all, an abundance of poetic imagery (in the fall, "maple leaves + puddle = crimson ships"; "raindrops × leaves = pearls on green plates" in the spring) and humor ("kitten + leaves + branches – meow = pussy willow"). Franco's clever mathcapades are boldly partnered by the strong, fluid lines and splashy palette of the appealingly retro artwork. Salerno (The Dirty Little Boy) also leverages the humor; he introduces a girl and her cat, tracking their activities throughout the year. His perspectives make the most of a migrating flock ("1/2w = v = flying geese") in a farmland scene as well as a close-up of orchard fruit ("apples + worms = sweet tunnels"). This book's jazzy, wholly original approach elevates basic mathematical concepts plus wordplay to the level of inspiration. Ages 5-10. (June)