Tying Shoes

Caleb knows how to tie shoes, kinda. He somehow manages to get them tied, but they don't stay tied for long. I bought a book that teaches how to tie. Caleb was practicing in the car the other day. I told him to tie his shoe, not the shoe on the book. I explained how I only had to tie my shoe once a day and they stay tied. He said that one of his shoes had stayed tie, all day! I asked what happened to the other one, that won't stay tied. "I just had one magic touch," was his reply. How do you argue with an answer like that?