Water is a liquid, which is the form most commonly recognized by young children. Explaining to preschool kids that the natural state of water is liquid can be illustrated by turning on a faucet, flushing a toilet or running a garden hose. The properties associated with water, such as being free flowing, are shown best by running water and explaining to kids that liquids are pourable. This is one way to begin discussions on the other properties of water and how altered states differ. For example, pouring a glass of water from a pitcher into a glass is a smooth movement, whereas pouring ice cubes in to a glass is loud and clunky.
Changing liquids to solids is one way to illustrate to small children how chemical properties can be alter through the addition or removal of heat. Making ice cubes is a fun way for preschool kids to begin grasping the concept of water being turned in to ice. Make ice cubes in fun shapes by using candy molds for freezing water. Serve up the fun ice cubes during lunch of snack time to get kids even more involved in the process.
Though boiling water is not a safe experiment for preschool children to attempt in a hands-on manner, you can use the front of a classroom to show young children how water changes in to steam. Using a coffee pot or electric tea kettle, fill the container with water and turn the unit on. Children can watch as the steam escapes from the container once the water has been thoroughly heated. To increase the results of this demonstration, use a whistling tea pot if you have a traditional stove available. Have kids stand far enough away from the boiling water, yet close enough to hear how the pressure of the escaping steam causes the tea pot to sing.
A fun way to illustrate to preschool children how water changes properties through the addition of heat is to place two clear glass bowls of ice on a table. Explain to children how frozen water is ice and once the ice begins to reach room temperature the ice will turn back into water. Allow both bowls to sit on the table for one to two hours. Have kids periodically look in the bowls to see how the ice is beginning to melt. Demonstrate how the addition of heat to the ice speeds up the process by using a hair dryer and blowing the side of one bowl to rapidly melt the ice.