Water can exist as a solid, a liquid, and a gas under various conditions. These are the phases of water. The conditions that cause a change of phase are interesting and important. Both temperature and energy play important roles.

	Icicles happen when the snow on the roof melts and then freezes again. It takes two changes of phase!

Main Pages	Estimated time required
Exploring change of phase	30 minutes
What happens when water evaporates? and Making Dew With What We've Got	60 minutes
What is the temperature pattern of ice water as the ice melts?	45 minutes
About phase changes, humidity, and boiling	45 minutes
Concluding the unit on phase change	30 minutes

Another page relevant to this section: Why study phase changes?

Materials needed for this section

• a glass jar, a can, a styrofoam cup
• thermometers*
• ice, ice water, hot water (please see local materials)
• liquid crystal sheets or thermometer*
• a glass vial
• pipette*