A Shapes Book

Every colorful page of Christopher Danielson’s children’s picture book, Which One Doesn’t Belong?, contains a thoughtfully designed set of four shapes. Each of the shapes can be a correct answer to the question “Which one doesn’t belong?” Because all their answers are right answers, students naturally shift their focus to justifications based on the shapes’ properties and attributes. They construct arguments supporting their choices, and strive to understand their classmates’ reasoning. They learn to look deeply at shapes and experience how creativity, beauty, argumentation, and conversation are all integral to mathematics. From kindergarten through calculus, students and their teachers gather around Which One Doesn’t Belong? to have rich, open-ended discussions about geometry.

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