I'm involved in the BSA as an Assistant Scout Master through the church... I work with boys 12-14 and sometimes 10-12. We had a game day and I have several, but here is one of them undoing a human knot.
It is a pretty fun thing to do... and can be done at parties for a mixer. Have each person grab a persons hand then grab someone else other hand with their other hand. Now the fun, unwrap yourselves so you are in a circle holding hands side by side. It took them about 20 min once all 15 boys were put in one knot.