Many have heard the "old wives tale" stating that if you put hot water into a freezer, it freezes in less time than it would have if it had been cold to start. Never did I believe such a claim, as it runs contrary to one of the basic laws of nature.
While surfing one day on sites illustrating "bad science" I actually found a plausible real life reason why this in fact can be true (read:not always true, but possible). Running this experiment under controlled conditions [eg. measure the same volumes of hot and cold water, make sure containers are equal in any relevant aspect (shape, material, conductance properties, covered or not etc.), and that the freezer is properly set to achieve a uniform temperature throughout], can you come up with a reasonable set of conditions for which the water in the hot container would freeze before the water in the cold container?
(In reply to
re: thoughts and considerations by Gamer)
It might not violate the conditions of the problem. Charlie referred to dissolved air, which might occur in an open container. It's not my specialty, but I would be willing to believe that hot water might dissolve more air from an open container than cold water.
Another possibility is that if both containers are open, some of the hot water might have evaporated, giving the freezer less work to do.
If it's a freezer with frost in it, hot water might melt some of the frost, which would otherwise act as an insulator between the container and the refrigeration coils.