Readout
The badge turns green when the bars sit inside the wiggle room you would expect for this many balls. Small runs look lumpy — that is the point of dropping more.
The board
Changing the rows or the lean re-runs every ball that has landed through the new board, so the histogram never goes blank. With Animate off, drops fill in instantly.
Inspect a bin
- Landed
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- Curve says
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- Routes in
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Click a bin, or focus the board and walk it with the arrow keys.
Why a bell?
A ball's whole life is a string of coin flips: L R R L R L ..., one per row.
Where it lands depends only on how many rights it got, not which order they came in.
There is exactly one route to the far-left bin — go left every single time. But there are thousands of routes into the middle, because there are thousands of ways to mix an equal number of lefts and rights. The bins in the middle are simply easier to reach, and the bell curve is that count of routes, drawn to scale.
Drag bounce right off 50% and the whole pile slides sideways and narrows — the same machine, biased. That is the everyday version of this shape: heights, timings, measurement errors, anything built from many small independent nudges.