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Subject pillar
General Knowledge
The useful facts are the ones that connect to others. This pillar collects the units, conventions and oddities that turn up everywhere else.
2 lessons · 1 quiz
Lessons
General Knowledge/beginner
How We Agreed on the Metre
Every measurement is a social agreement backed by physics. The metre's history runs from a survey of the Earth to the speed of light — and shows why standards matter.
5 min read
General Knowledge/beginner
Why a Week Has Seven Days
Nothing in astronomy produces a seven-day cycle. The week is a social invention that spread because it was useful — and it left traces in the names of the days.
4 min read
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