Handcuff Puzzle

Type of strategy: CollaborationGamesHumor and CelebrationMovement

Learning styles: ES: Extraversion and Sensing

This is a classic puzzle that has been around for at least 250 years. It is very challenging, but it does give students a chance to get students up and moving. It depends on lateral thinking and topology (rubber geometry or the mathematics of distortion). It can also make a good party game (for adults too). 


Setting Up

For this puzzle you need two people, some rope and some empty space to do the puzzle in. Each person will need a piece of rope with a loop tied in both ends, so it can be worn as handcuffs. The rope should be reasonably long, so that the person wearing it can easily step over it if they want.

Each person puts on a complete set of handcuffs. Before putting them on, they loop their handcuffs around each other so they are tied together. Each person should wear a complete set of handcuffs. They then have to get themselves apart while following these rules:

The Rules

The handcuffs cannot be removed.

Do not break, cut, saw through, bite through or in any other way damage the rope. Damaging each other is probably a bad idea too.

If you are doing this puzzle with a class, make certain you tell them they need to be able to show you their solution. Otherwise it won't be so enjoyable.


The Solution

Imagine you are one of the people doing the puzzle. Start by moving the other persons rope along yours until it is lying on your arm. Make sure that the other person's rope is not wrapped around your rope, it should only be touching your arm. You can see now that if you could pull the rope through your arm, the puzzle would be solved. However, this would be very messy and not have a lot of repeat potential. Instead, you need to move it around your arm. 

Reach in through your handcuff with a thumb and finger; and grab the other person's rope. Now pull it through your handcuff and over your hand. It should now be on the other side of your arm. Now let it go back through the handcuff and you are separated.

Solution Visuals: http://britton.disted.camosun.bc.ca/jbhandcuff.htm


If you are showing this one to a class, some students will say that the puzzle is easy and they know how to do it. Don't worry, they don't. The first thing they will do is either step over the other person's rope or duck under it. This will not work.

People very rarely solve this one without assistance. Some hints that may help is to get them to stand within arms reach of each other, then tell them that they do not need to move their feet. Alternatively, explain to them that it is impossible to unlink two linked rings, but they are not two linked rings, there is a gap at each wrist.

If you are working with a single pair, you can lead them to the solution using a rubber band.

First have one student take off a handcuff, put the rubber band on their arm and get them to put the handcuff back on. Ask them to take the rubber band off their wrist without getting it caught on the rope. They will take it under the handcuff.

Next put the rubber band back on their arm but this time hold onto one point on the band. They will take it under their handcuff again, but this time they will have to stretch it over their hand and let it go back again.

Now use their partner's rope in the place of the rubber band.



Submitted by: Thomas Edge