The Cat's Cradle.
Essentially it's just a loop of string.
Two girls take it in turns to manipulate this string with their fingers.
When I was younger, I found it a powerful one to one socialising aid.
I was literally tethered to the other girl, so I couldn't run away.
(If we decided to use alternate hands, one hand to hold the string and the other to move it). Or we could take in in turns to use both hands.
This physical bond helped to enhance the social bonding.
It was concrete. I couldn't grasp girly chatter: it was too nebulous, gaseous and had no tangible physical form. I needed a touchstone: a focus for the interaction. Something to fidget with.
This deceptively simple little string could be manipulated into lots of interesting shape patterns. I had to cooperate with the other girl in other to view the next pattern.
The patterns were in a sequence, like musical chords.
Each pattern had a name: tramlines, the manger, the diamond, the bedsheet.
This helped me with my Maths (sequences) and my musical education.
In short, sometimes the simplest toys really are the best.
I made a lot of friends cats cradling.
The headmaster was so impressed with the cat's cradle that he had me do a presentation in front of the whole school. Everyone seemed in awe at two girls (my friend and I) joined together by a loop of neon coloured string.