Delores Jean Brooks - Percy Lavon Julian H. S. 



The Water Cycle
     
Delores Jean Brooks            Percy Lavon Julian H. S. 
                               10330 South Elizabeth
                               CHICAGO IL 60643
                               (773) 535-5170 

Objective(s):
    
    Grade level 9 Regular/Inclusion

     1. To introduce and model the concept of the water cycle.
     2. To show how water is circulated from Earth's water sources through the 
        processes of evaporation and condensation.
     3. To show how substances dissolved in water can be separated and/or 
        recovered through the process of evaporation. 

Materials Needed:

     Activity 1: Illustration of the water cycle, container of water, eye 
                 dropper, small plastic slide.
     Activity 2: Aluminum pan, crushed ice, salt.  Clear plastic 2 liter 
                 bottle, warm water, ice cubes. 
     Activity 3. Hot plate, clear flask or kettle w/spout, rubber tubing 
                 about 12in./30cm, clear wide rimmed glass, ice cubes, 
                 aluminum pan and 4 teaspoons of salt.

Strategy:

     Activity 1. Display illustration of The Water Cycle.  Prepare slides for 
                 each student, placing 1 drop of water per slide and 
                 distribute (state, save for later observation).
     Activity 2. Fill aluminum pan with crushed ice, add salt, stir slightly. 
                 Wait about 15 minutes.  See snow appear on outside, and bottom
                 of pan.     
                 Fill clear plastic 2 liter bottle with 1/2 liter warm water.
                 Place ice cube on top of bottle opening.  See vapor (cloud)
                 form, wait, observe drop formation, see drops (rain) slide 
                 down side of bottle.
     Activity 3. Fill flask or kettle with 1 cup of water and 4t salt.  Stir
                 till dissolved.  Connect rubber tubing to kettle or flask 
                 spout, extend rubber tubing so that middle sits in aluminum
                 pan (may need to be taped down) cover with ice cubes.  Allow
                 open end of tubing to flow into a clear glass.  Boil salted 
                 water until all water is evaporated.  Observe.
            
Performance Assessment:
     
     Activity 1. Did water on slide evaporate? Where did it go?  If not, state 
                 possible reason, high humidity? not enough time lapsed???
     Activity 2. Did snow (frost) appear on outsides and bottoms of pan?
                 Did water vapor rise and form on the sides of plastic bottle?
                 Did vapor droplets form and roll down the sides of plastic 
                 bottle?
     Activity 3. When salt was dissolved in water how did water's appearance 
                 change? 
                 When salted water was boiled and vapor cooled, what was left 
                 in the kettle or flask?
                 What was formed in the clear glass?

Conclusions:

     Activity 1. The students will observe that the water droplet evaporated 
                 if the air was dry enough for evaporation to occur, as water
                 is evaporated from our earth's surface. 
     Activity 2. The students will observe snow (frost) and cloud (vapor)
                 formation, and rain (water droplets) and associate these
                 activities with the Earth's collection of water vapor from
                 it's many water sources and the processes that occur to 
                 change those vapors into rain and snow before they fall again
                 and again to the earth's surface.
     Activity 3. The students will observe the process of distillation, which
                 may be used for various purposes, but is introduced as a way
                 of removing the salt from sea (ocean) water.
                 
References:

     Today's Basic Science, The Scientist and Tomorrow, Navarra and Zafforoni,
       Harper & Row, U.S.A., 1971.
     Water Science, Water Fun, Great things to Do with H2O, Fiarotta & 
       Fiarotta, Sterling Company, Inc., New York, 1996.