One of my first jobs was substitute teaching for a special education class in Hawaii. It was a team teaching situation, and one of the teachers was out for more than half the year, so I was the replacement. The other teacher and I kept a jigsaw puzzle going in one corner and worked on it during breaks.
One of the other teachers gave us a puzzle called "Little Red Riding Hood's Hood." It was a big solid red circle, weirdly shaped pieces, very difficult. One day when the puzzle was barely started, one of our special ed students came by the table, looked at the pieces, picked one up, and casually put it in. IT FIT!!! As far as I know, he never tried to put another piece in another puzzle. Could he have done so? I have always wondered.