Topology

In topology, a coffee mug and a doughnut are the same shape. Explore what survives stretching and bending: holes, one-sided surfaces like the Möbius strip, the Euler characteristic, knots that can't be untied, the theorem that says you can't comb a hairy ball flat, worlds built by gluing the edges of a square, and why every map of a park laid inside that park has one point exactly over the spot it shows.