Family mode

Watch this one together

~5 min · materials: an ice cube and a clear glass of water (optional, to try it yourself)

Why does ice float?

An ice cube bobbing in a summer drink — or a winter pond that freezes a lid on top so fish and frogs survive underneath; the iceberg that hides nine-tenths below.

Talk about it

  • Guess first: does a cup of ice weigh more or less than the same cup of water?
  • Only about a tenth of an ice cube pokes out — where is the rest of it?
  • Most solids sink in their own liquid; why do you think water breaks the rule?
Watch it together

no login · nothing saved · pass the phone around

Daytime browsing? Explore every question · Teaching a room? Classroom mode