Left: The large rectangle is plastic and can be split into a square (blue) and two plastic rectangles (red and {green).
Centre: The two arcs drawn in each square.
Right: A Harriss spiral.
Image: Chalkdust.
More from Chalkdust

Dear Dirichlet, Issue 11
Grant applications, musical media and last-minute Olympics training are the topics readers have sent in to the professor's postbox this issue
In conversation with Clifford Cocks
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Star polynomials
Natalya Silcott introduces us to star polynomials!
Making your own papercupter
Next time you are finished using a paper cup, create your own papercupter!
Top Ten: Parts of a circle
The definitive chart of the circle's greatest parts
Proof by storytelling
Sit in your favourite chair and do away with those tedious algebraic proofs
