A child steps through a die-cut bedroom window into a wonderland of math- and number-related concepts.Prompted by a note hidden beneath a flap, Molly finds herself first in a world (with, significantly, a white rabbit) where select insides and outsides are inverted. Subsequent flaps see her finding and passing through further concealed doorways into an M.C. Escher–style "impossible staircase," a maze with tessellated shapes, a set of infinitely receding hallways, and six more "implausible but not impossible" settings that likewise demonstrate some of math's central tools and ideas-often in an interactive way that requires folding, recognizing patterns, or interlacing pre-cut elements. Artymowska fills her big, square illustrations with both clearly drawn examples of each main concept and smaller details to search out, such as sets of nesting dolls to match up. (A tiny mouse and even the rabbit show up now and then, too.) Spurred by a reminder that inverses can themselves be inverted, Molly, depicted as a small child with light brown skin, a black pageboy, and a bright, inquiring look, rides through wormholes back to her room for a well-earned rest…but Cheng carries on with second looks at 17 notions met along the way, from types of symmetry to fractals, Latin squares to logical paradoxes.Considerably more than six "implausible but not impossible" things to believe before breakfast…and after. (Informational novelty. 6-11)

A child steps through a die-cut bedroom window into a wonderland of math- and number-related concepts.Prompted by a note hidden beneath a flap, Molly finds herself first in a world (with, significantly, a white rabbit) where select insides and outsides are inverted. Subsequent flaps see her finding and passing through further concealed doorways into an M.C. Escher–style "impossible staircase," a maze with tessellated shapes, a set of infinitely receding hallways, and six more "implausible but not impossible" settings that likewise demonstrate some of math's central tools and ideas-often in an interactive way that requires folding, recognizing patterns, or interlacing pre-cut elements. Artymowska fills her big, square illustrations with both clearly drawn examples of each main concept and smaller details to search out, such as sets of nesting dolls to match up. (A tiny mouse and even the rabbit show up now and then, too.) Spurred by a reminder that inverses can themselves be inverted, Molly, depicted as a small child with light brown skin, a black pageboy, and a bright, inquiring look, rides through wormholes back to her room for a well-earned rest…but Cheng carries on with second looks at 17 notions met along the way, from types of symmetry to fractals, Latin squares to logical paradoxes.Considerably more than six "implausible but not impossible" things to believe before breakfast…and after. (Informational novelty. 6-11)