Family mode

Watch this one together

~6 min · materials: none

Can two friends build the same hidden number while a listener copies every public card?

Two friends need matching locked boxes, but every card they exchange crosses a bridge where a curious robot can copy it.

Talk about it

  • Name every public card and every covered value before the listener begins.
  • Why can two covered results match even though neither result crossed the bridge?
  • What extra job does authentication do that hard mathematics alone cannot?
Watch it together

no login · nothing saved · pass the phone around

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