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Rope Handcuffs

Get your students’ minds all tied up with this rope puzzle.

They’ll have to use lateral thinking and topology to untangle themselves from their partners.

Topology is the mathematical study of shapes and spaces. It involves looking at the shapes that result through stretching, transforming, deforming, folding and twisting. Tearing, on the other hand, is not allowed!

Magic is something that seems otherworldly or mysterious. Magicians entertain us by creating the illusion that they have strange and mysterious powers.

In the world around us, we can get by without having a good understanding of how everything works. For many of the complicated gadgets that we use, the science is hidden inside the “black box”. So it may seem to work “like magic”. Science-fiction writer Arthur C. Clarke claimed that “any sufficiently advanced technology is indistinguishable from magic”. If we understand why things happen based on our observations or previous knowledge, things don’t seem as magical anymore.

Objectives

  • Explain the importance of observation when doing science.

Materials

  • Per Pair:
    String or rope, pre-cut into metre lengths

Key Questions

  • Why does this solution work?

What To Do

  1. Each student receives one rope and ties loops on either end large enough to insert their hands like a pair of handcuffs.  Tip: the loops should be loose enough that students can easily take their hands out for safety purposes. It will also make the trick easier to accomplish.
  2. Pair students and have them each put on their handcuffs so that they are linked together.
  3. Students now need to figure out how to separate themselves from their partner without removing the handcuffs or breaking or damaging the ropes in any way. They must be able to show you how they accomplished it.

The Solution: 

  1. Lay your partners rope on your arm. You should be able to see that you could pull the rope through the loop on that arm, if only your arm weren’t in the way!
  2. To get around your arm, reach through the loop of your cuff and pull your partner’s rope through the loop towards your hand, and bring it over your hand to the other side of your arm.
  3. You should now be able to slide your partners rope through the loop of your handcuff!

Extensions

  • Using what you learned from this puzzle, can you invent another puzzle using ropes?