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We’re thrilled to be introducing a new weekly feature here on Make: Online: Math Mondays. Every week, guest author George Hart, from the newly-formed Museum of Mathematics, will post a fun, experiential, puzzling little item, exploring some intriguing aspect of mathematics. The Math Museum is dedicated to raising people’s awareness of the wondrous mathematical patterns and structures that exist all around us. They do this through such experiential means as their Math Midway, a traveling circus of hands-on exhibitions, that brings math to life in tangible and fun ways… and now, through a weekly column on MAKE.

We hope you’ll make George feel welcome, and that you’ll get a good educated kick out of what he’ll be offering up each week. This week, he starts by offering up… breakfast. — Gareth

Mathematically-Correct Breakfast


Start your day right by making this challenging bagel cut, and see if you’re really awake yet. Can you figure out how to slice a bagel into two congruent halves which pass through each others holes, like two links of a chain? Hint: The motion of the knife follows the surface of a two-twist Möbius strip. If you hack up a dozen bagels and still haven’t solved the puzzle, you can check out the instructions here.

[Editor's note: Although the cream cheese might make it hard to discern, these two bagel halves are continuous and inter-locked.]

All About George:
George W. Hart is a research professor in the computer science department at Stony Brook University, NY. He holds a B.S. in Mathematics and a Ph.D. in Electrical Engineering and Computer Science, both from MIT. He is the author of a linear algebra monograph, Multidimensional Analysis, (Springer Verlag, 1995) and a geometry text, Zome Geometry, (coauthored with Henri Picciotto, Key Curriculum Press, 2001). Hart is a sculptor developing innovative ways to use computer technology in the design and fabrication of his artwork. His sculpture has been exhibited around the world and can be seen at He is also very active in developing novel construction workshops as ways to communicate the richness and excitement of mathematics. Currently, Hart is on sabbatical, working to start up the hands-on Museum of Mathematics.

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.

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