Build a small, self-contained interactive page that lets a human understand code or results by playing with them — a parameter playground, an execution timeline scrubber, or a side-by-side behavior comparison — always on real project data. Use when behavior is easier to inhabit than to read about — calibration or threshold trade-offs, state machines, parsers/interpreters, dynamic or emergent behavior — or when the user says "I can't picture this", "show me how this actually behaves", "let me play with it", "build me a playground / visual debugger". Single-use teaching UIs are cheap now; understanding is not.
