BAKE INFINITE PIE WITH X + Y

Two light-skinned children named X and Y, apparently siblings, ask their brainy aunt, Z, to help them make the pies of their dreams.

X wants to make an infinitely wide pie, while Y imagines a pie that is infinitely tall. Aunt Z explains that “there are infinite different ways to make pastry” and guides the children through the steps of the recipe. When it’s time to roll out the dough, X makes a circle while Y makes a triangle. When they fill the pies, X chooses bananas “because the slices are round,” and Y opts for triangular strawberry slices. Once in the oven, the pies seem “to be taking infinitely long” to bake and smell “infinitely delicious,” and when they’re finished, they’re so scrumptious the kids want them to last forever. Luckily, Aunt Z knows a clever way to make “infinite pie.” She helps the children make yet more dough and shape it into fractals—the Apollonian gasket and the Koch snowflake—that have an infinite number of sides. In the process, Aunt Z explains mathematical concepts (further expounded in the backmatter) in accessible language, including the coordinate plane, combinatorics, polygons, and convergence. This discussion includes a fair amount of precalculus for readers who might not have mastered the times table as yet, but as Cheng says in her author’s note, “if we can get our heads around something daunting, then [we] become more intelligent.” After the baking is done, the characters have more pie than they can eat, but thankfully, they have “infinite friends to share it with.” The illustrations, done in ink and Photoshop, use clever visuals to bring the math lesson to life; for example, on one spread the pie ingredients zoom around the characters, the motion lines making the shape of the infinity symbol.  

Not a page-turner but a charming—and appetizing—bit of didacticism.