Why the World’s Best Mathematicians Are Hoarding Chalk

Mathematicians developed a near-cult attachment to Hagoromo, a Japanese chalk brand so smooth on a blackboard that professors started buying it by the case and stockpiling it before the company briefly stopped production. The short traces why a two-dollar box of chalk became something departments quietly hoarded like a rare vintage.

Why it's free: Free on Great Big Story's own channel; Great Big Story produced it in-house.