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
Counting caterpillars
Peter Rowlett uses combinatorics to generate caterpillars
Carnival of Mathematics 162
This month’s round up of mathematical blog posts from all over the internet
Domino tiling & domineering
John Dore and Chris Woodcock join the dots
Thinking outside the box
Negative polygons and other mathematical creations
Advent Calendar: 24 December
It's the last day of the Chalkdust advent calendar, so there must be something very good behind today's door...
@mathslogicbot
Explaining the tautological Twitter bot