understand
Interactive explainers for curious 10-year-olds, built one idea at a time with simulations you can poke. Plus the prompts that made them and the reviews that fixed them.
Topics
Euler's formula for solid shapes: corners − edges + faces = 2
Count a football, find the pattern, then prove it can never fail. 12 sections, 16 live shapes. For a 10-year-old alone, two sittings.
The Number That Never Changes built from the prompt alone
Let's Squash a Football built with a page contract
the prompt
Let's Squash a Football built with a page contract
the prompt
Euler's identity: eiπ + 1 = 0
Multiplying is stretching and turning. Do a tiny turn many times and you walk round a circle. 10 sections, 10 live sims. A 12-to-14-year-old alone, or a 10-year-old with a parent.
Let's Walk Round a Circle built from the prompt alone
Spinning to Minus One built with a page contract
the prompt
Spinning to Minus One built with a page contract
the prompt
How they were made
- Adversarial review of the prompts and first pages
- Learner pass: each section read as a 10-year-old
- Cold run: the revised prompts handed to fresh agents, compared
- Two Claude Code skills that repeat the process for any topic
Modelled on "Let's Build a Brain" by Aatish Bhatia and Arkarup Banerjee. Source on GitHub.