You need: paper, 8.5 x 11 shoelace or string, at least 36" long rubber band

Fold the paper in half the long way, Figure 2. Then roll it into a tube, Figure 3. The tube is held secure by wrapping a rubber band around one end of the tube.

Stretch the shoelace out to its full length on the table. Place the tube on top of it, Figure 4. Cross end B over the tube and to the left so it as shown in Figure 5. Then bring end A up in the direction of the arrow in Figure 5.

End A is now in the position shown in Figure 6. Bring end A under the lace and to the right, in the direction of the arrow in Figure 6. The result is that you have knotted the lace around the middle of the tube, Figure 7.

Bring the end A through the tube in the direction of the arrow in Figure 7. End A is now in the position shown in Figure 8.

Grasp the end of the tube with the left hand and the knot with the right hand, Figure 8. Slide the knot off the tube in the direction of the arrow in figure 8.

Grasp an end of the lace in each hand and pull, Figure 9. Allow the tube to slide off the lace. The knot has vanished.