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Watch this one together

~5 min · materials: optional: a handful of beach or sandbox sand and a magnifying glass to see that the grains are rounded.

How do collision history and source shape sand grains?

Sitting on a beach pouring sand through your fingers and wondering how there could possibly be that much of it, all so tiny and round — a perfect summer-vacation question.

Talk about it

  • Pour some sand through your fingers and ask: there's way too much to count — where could all of this possibly have come from?
  • Look at a grain up close: it's round and smooth. A chip off a rock is sharp. So what happened to the grain to wear it down?
  • Next time you see a mountain or a cliff, ask: is the river at the bottom slowly turning that into sand right now?
Watch it together

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