Physics olympiad problem sets rendered in academic HTML, with official solutions, Claude's own solutions, and criterion-by-criterion self-assessments against the grading schemes.
An interactive web simulation of the trick behind the first black hole image: draw your own sky, scatter radio telescopes across a world map, and let the Earth's rotation combine them into a single planet-sized telescope that reconstructs your drawing.
A web simulation of Mark Kac's 1966 question: draw any drum shape, see its vibration spectrum and Chladni-style mode patterns, and hear how it would sound.
A physicist's resolution of the "expanding space stretches photons" picture: accumulated Doppler shifts, parallel transport, and the Bondi decomposition.
A hands-on electronics series for a young child and a science-fluent parent: build-it-yourself projects with from-first-principles explainers for the grown-up.
Arithmetic drills that get harder only as you get better — start with tiny sums and work up. Progress is saved on the device.
A one-page, print-friendly cheat sheet: turns, rent, building, jail, trading and bankruptcy at a glance.