Students use changes of state to create chilly architecture and some slippery slopes!
Salt lowers the freezing point of water. As it dissolves, the ice melts around each grain of salt. As a result, the ice is unevenly eaten away, forming a pitted, non-skid surface. This is why salt is used to melt ice on roads and walkways.
The salty water also re-freezes on the surface of the ice cubes, joining them together. This happens because the insides of the ice cubes are much colder than the freezing point of water. They are cold enough to draw heat out of the newly melted water and it re-freezes.