ALA Booklist
The basic plot is as tired as they come: a little Whatever wants to be Something Else, but finally decides that being a Whatever is best after all. In this case, Burns give the story a geometric twist: a little triangle who's tired of being a triangle goes to the shape-shifter, who adds one more side and one more angle, making the little fellow a quadrilateral. It soon grows tired of being a quadrilateral, though, and returns to the shape-shifter to gain another side and angle, and another, and another, until the poor little polygon is almost circular. Eye-zapping graphics, airbrushed acrylics with colored pencil, give the crowded pages some pizzazz. Burns' appended notes for adults discuss the terminology and concepts and suggest activities to increase children's understanding of geometry. Useful, perhaps, as a supplement to the math curriculum. For another Marilyn Burns Brainy Day Book, see Friedman on p.1004. (Reviewed February 01, 1995)
Horn Book
Three titles attempt to integrate basic mathematical concepts such as counting and geometry into fictional stories. However, the stories are contrived and not very entertaining, and the math is thinly veiled. While the extensive appended notes for adults are designed to explore the concepts further and help encourage discussion, some may find these sections a bit patronizing.
Kirkus Reviews
Here is a basic lesson in geometrical shapes disguised as entertainment. It aspires to nothing more, and just barely succeeds on its own modest level. The premise is that a busy triangle gets tired of its life and goes to a shapeshifter for an extra angle. Life as a quadrilateral is exciting for a while, but soon the protagonist requires another angle, and—the etceteras take readers through the final two-thirds of the story. Burns (The I Hate Mathematics! Book, Little, 1975, etc.) is wise enough to summarize everything past the hexagon stage. Notes on mathematics for adults working with children appear in the final pages. Newcomer Silveria takes the obvious approach to the illustrator's quandary—how to humanize an abstraction—by adding cute oval eyes and chubby cheeks. His creation comes off like a candidate for the Olympic mascot tryouts; he has a good color sense, and goes full throttle on every page. This installment of the `` Marilyn Burns Brainy Day'' series is static, simplistic, and too long by half—but finding fault with it as a work of art is like looking for character development in a Barney episode. (Picture book. 6-9)"
School Library Journal
PreS-Gr 1--An offbeat introduction to geometry. When a triangle tires of having only three sides, he asks the shapeshifter to change him first into a quadrilateral, then a pentagon, a hexagon, and so forth until he realizes he is happiest as a triangle: he can hold up a roof, be a slice of a pie and, best of all, slip into place when people put their hands on their hips. ``That way I always hear the latest news...which I can tell my friends.'' The text is clever and shows more than the usual places to find shapes--part of a computer screen, a section of a soccer ball, a floor tile. The acrylic and colored-pencil illustrations are colorful, abstract, and filled with smiling shapes done in shades of turquoise, pink, and yellow. A two-page spread of suggestions for adults to reinforce the math lessons featured is included at the end of the book.--Christine A. Moesch, Buffalo and Erie County Public Library, NY