Why do icicles form on the south side of buildings? Icicles are created by repeated melting and freezing of water. The sun melts the snow during the day and it freezes in the night. Melting does not occur as frequently on the north sides of buildings, as the sun is in the south! Why do we grit the roads? Adding impurities to water affects the temperature at which it freezes and boils. Adding grit means that water will freeze at a lower temperature, and may not freeze at all.

	Activity One
	Measure how much melted snow it takes to make water. Collect some snow in a container and record the level of snow on the container. Let the snow melt. How much water is there? Are you surprised at the difference?
	Activity Two
	Take two ice cube trays. Fill one with a cup of water. Fill the other from a cup of water with a teaspoon of salt dissolved in it. Observe which of the trays solidifies first. The salt-water tray will take longer to freeze. This is because the salt has lowered the freezing point of the ice, and therefore it takes longer to freeze.
	Activity Three
	Cutting through ice. Take an ice cube and place it on the mouth of a bottle. Take a piece of wire and twist each end around a rock. Place the center of the wire over the ice cube and observe. The wire will slice through the ice cube and as it does so the ice will refreeze above the wire. It is thought that the pressure causes the ice to melt.