(1) Have an adult hold the slinky horizontally, pointing at a six-year old boy.

(2) Have a 6-year old put his small hand through the slinky and grab the far-end (i.e. nearest the adult).

(3) [Optionally, for easier handling.] Have the adult twist the far end of the slinky slightly to the right, to widen it. Have the child twist the far end of the slinky to the right, to narrow it. [These identical instructions giving different results makes sense because they are looking in opposite directions.]

[4] Threaten, or otherwise coax, the 6-year old to drag the tip of the slinky through the middle of the body.

[5] Keep threatening, so the 6-year old keeps backing away.

Voila! A slinky that has reversed in orientation, just as you described.

See also: Reversing direction of a curly telephone cord, which uses a different technique.

The only trouble is that I didn’t go through the middle either. And the 6 year old wasn’t involved at all except as the recipient of some comments about the length of time between the acquisition of the slinky and it becoming tangled.

Now that I’ve thought about it some more (note to self: think THEN blog), I think what I did was open the slinky like a book, pulling out a ring and in the process twisting it over. From there I think it’s possible to wind the twist all the way to the other end of the slinky and create the desired effect.

It’s still hard to wrap my head around though; I’d need to actually try it. Next time we get a tangle I will.