there was a kid in my high school calculus class who would get all of the right answers to questions, but was never able to explain how he did it. the teacher would make him write out his work on the board and he could certainly transcribe the entire sequence that lead him from problem to solution. but there was always a step or two, a leap you might say, that made sense only to him. for not being able to totally prove his theory yet still coming up with the right answer, he got half credit.
in clothing construction class, i too would receive half credit. my attempt at making the amy butler anna tunic seems to be complete...but don't look too closely or you'll be able to poke many holes in the theory and there will be no explanations to offer. just the fact that it came out sort of right, but who knows how it got there.
oh, and that kid, he's now a mathematician working for nasa.