Supercooling

=Supercooled Water=

Very pure water can be cooled to a temperature a little bit below it's freezing point without actually starting to freeze. Adding an impurity or an ice crystal or sometimes even just banging on the container will kick off the freezing process. The following videos are good to show in class. Actually performing a supercooling demo in a classroom would be tricky because the timing and conditions would need to be just right.