SCIENCE!!: While I was doing some research on air I came across several references to a myth that hot water will freeze faster than cold. Some referred to this as the Mpemba effect and that it stemmed from a young boy in Africa (named Mpemba) who did some experiments to prove this. Many “scientists” tried to duplicate the findings. While many of them were unable to duplicate this experiment, others have determined that there may be some validity depending on what is in the water (for example, we know that salt water freezes at a much lower temperature than fresh water), atmospheric and other conditions. Something as simple as the shape of the container may affect how fast the water freezes.
While the science behind this phenomenon is complex, the experiments themselves can easily be done by the youngest of students. And this can be a great introduction to the scientific method, and making sure there is only one difference between the various test samples. The water in one country obviously will have different impurities than the water in another country. The barometric pressure changes from day to day. All of these things will need to be taken into account, but this effect happens sometimes and we still aren’t sure why. Perhaps some of your classes would like to see if they can figure it out.
Give it a try, see what you come up with