The Jumping Knot
Two ropes of equal length, one red, one white. A knot tied in the white rope jumps across to the red rope, and when the white knot is untied it’s seen that the white rope is woven into the threads of the red rope.
You can also view this trick on YouTube at https://youtu.be/b2CQEToGmHE
You can see all the previous magic lessons here.