Watercycle

Clara Phillips                 Dawes Elementary                 
                               3810 W. 81st Pl.
                               Chicago, Ill. 60610
                               312-838-5250 

Objectives:

   Grade level 3
To become aware of the natural circulation of water from oceans, lakes and 
     rivers by evaporation into the air.
To know that condensation occurs to produce rain falling to the soil, running
     off to rivers, lakes and then to the ocean once again. 

Materials Needed:

A teakettle, about 18 inches of tubing, a clear glass bottle with a narrow neck, 
ice, a pan large enough to contain both the bottle and ice water, and a heat 
source.  NOTE: These materials should be used by the teacher. 

Strategy:

1. The lesson will begin with a review of cloud formation.  The science textbook 
has stated that clouds are made up of tiny drops of water.  Our experiment will 
help to prove this fact. On the chalkboard there is a chart naming and defining 
some of the clouds: cirrus clouds, cumulus clouds, stratus clouds, and nimbus 
clouds. 

2. There will be a discussion of the three steps in the water cycle: 
          evaporation, condensation and precipitation.
The sun causes water to evaporate.  The moisture meets colder air and condenses
forming clouds.  When droplets in a cloud are too heavy the water falls to the 
earth as precipitation.

3. Do the following experiment:
Pour a pint of water into the kettle and attach the tubing to the spout of the
kettle as airtight as possible.
Place the other end of the tube in an empty bottle.
Place the bottle with the tube in a pan, pack ice around the base of the bottle. 
Boil the water in the kettle until you see a few drops of water collecting
inside the bottle.

Conclusions:    

     The energy from heat speeds up water molecules and some move so rapidly 
that they evaporate or escape into the air as gas or water vapor.  As more 
molecules rise they push into the tubing and pass through it to enter the 
bottle, which has been cooled by the ice.  At that stage the cold air slows down 
the gaseous water molecules and they come together or condense, once again 
returning to the liquid state. 
     On earth there is a natural circulation of water from oceans, lakes and 
rivers by evaporation into the air.  Then condensation occurs to produce rain 
falling to the soil, running off to the rivers, lakes and then to the oceans 
once again.