Anyone with a small child has experienced the frustration of a twisted slinky. Frustration, however, often leads to a stretched out, unusable toy. Fixing a twisted slinky doesn't need to be frustrating, though, because it is actually very easy to do. It just takes a few patient moments to untwist a slinky, which is better than having to explain to a crying child why his toy is destroyed.
Place your four left-hand fingers inside one end of the slinky and place your left thumb on the top, outside of the coils.
Stretch the slinky out slightly until you see the backwards coil. It is usually easy to detect since one coil will be sticking out a little further than the rest of them. When you stretch the slinky out, the backwards coil will look like an upside-down "U."
Grab all coils up to the backwards coil in your left hand and hold firmly.
Hold the slinky from the other end with your right thumb on the top, inside of the coils.
Turn your wrists in opposite directions until your left thumb is on the bottom, outside of the coils.
Include the newly twisted coil with the other coils in your left hand by grabbing it with your left thumb and fingers and removing your right hand.
Continue twisting the coils this way until you have reached the right end of the slinky and all coils are twisting in the same direction.
If you are untwisting a plastic slinky, be sure not to stretch the slinky out too far or bend the coils on an angle. The coils can easily snap in half if they are bent or stretched out.