The Greedy Triangle is a most unusual book in that it will appeal to three age groups, 4-5 year olds, those learning polygons for the first time, and for adults who never felt that comfortable with geometry. The book opens up the reader's mind to seeing geometric shapes all around, while providing a simple basis to remember the differences among polygons (they each differ in having one angle and side more or less than the most similar polygon).
"Once there was a triangle that was -- as most triangles are -- always busy." The book points out some of the many frequent places where triangles can be found such as "holding up roofs, supporting bridges, making music, catching the wind for sailboats, being slices of pie . . . and more." "The triangle's favorite thing, however, was to slip into place when people put their hands on their hips." This last refers to the space between the arm and the body. The triangle likes this shape because "that way I always hear the latest news . . . which I can tell my friends." And his friends like that.
But the triangle finds this boring at some point, and seeks the help of a shapeshifter to become a quadrilateral. Ennui recurs and the former triangle moves through a transition successively into a pentagon, hexagon, heptagon, octagon, nonagon, and decagon. For the first few shapes, the book outlines places you find these shapes in nature and human-made objects. A connection is also made as to whether those shapes provide juicy stories to tell friends. There is adult humor, such as noting about not being able to tell secrets learned at the Pentagon.
Eventually, this all becomes self-limiting. "Its sides were so smooth it had trouble keeping its balance." "Its friends couldn't tell which side it was on and began to avoid the shape." The shape fell down a hill. "It felt tired and dizzy, lonely and sad." "I want to be a triangle again." The shapeshifter said, "I'm not surprised."
The book has an excellent guide in the end for parents, teachers, and other adults. This includes great exercises to extend this knowledge for your child. This section also explains the terms more precisely, and defines an undecagon (11 sides) and dodecagon (12 sides).
The illustrations are in bright, electric versions of pastel colors that effectively emphasize simple shapes in their most abstract forms.
I was impressed by the sections that use examples of the shapes. Some of them I had never thought about before. This is a great way to stimulate subconscious learning. I also enjoyed the many "punny" expressions, obviously designed to amuse the adult readers. If you don't like puns, you will probably think the book is a little corny.
The book's only weakness is that the story is too predictable. That limits its appropriateness for older children. They need more complications in their stories. Since the book is aimed 4-8 year olds, it doesn't hurt a bit for the 4-5 year olds but will lose you some 6-8 year olds. This predictability is fine for new geometry students, because getting to read something more interesting than a textbook is a thrill at that point. For permanently polygon-puzzled adults, the book will seem very down-to-earth and accessible.
I also suggest that you ask your child to extend the contents of this book to identify other shapes that are not polygons (such as circles) and specific types of polygons (such as squares, parallelograms, and trapezoids). You can use the exercises in the end of the book towards these shapes, as well.
Reshape your perceptions of polygons!
