3. Now take the second loop you just created and pass it through the circle a second time, in the same direction you used the first time.

6. To untie the shoes, firmly pull on either end of the lace.

P.S. In trying out these instructions with dozens of willing subjects, we've come to realize that everyone ties shoes differently. So the pictures here may not correspond exactly to the way you do it. But the principle of the double loop is the same -- and the knot will work -- whatever your shoe-tying technique.