Water Cycle - Water (5)
Pre Lab 

   
OBJECTIVES:
  • Introducing the water cycle.
  • Analyzing why water is important.
VOCABULARY:
  • condensation
  • evaporation
  • precipitation
  • water cycle
MATERIALS:
  •  worksheet 

Students use a worksheet to trace the water cycle.

    

BACKGROUND:

Water is our most common natural resource.  It is essential to the biology and chemistry of all living things, it plays a major role in shaping the earth and is an active agent in many physical reactions. It is important to most life to keep it clean.

There is plenty of water on Earth, but 97% of this water is saline (contains dissolved salts).  Only 3% is fresh and about two thirds of that amount is locked up in polar ice caps and glaciers; about one third can be found as ground water, lakes, and in the atmosphere.

Water exists in three states of matter:  solid (ice), liquid (water), and gas (vapor) at normal conditions.  Water is a colorless, odorless, tasteless liquid with a melting point of 0° centigrade and a boiling point of 100° centigrade.  

Water can be easily cleaned through the water cycle.  When water evaporates in the gaseous phase, it leaves all the impurities behind.  Water can also be cleaned through other natural ways.  Humans have created ways in which they can also clean water without going through a natural water cycle.

PROCEDURE:

  1. For the next four weeks, students will look at the properties of water, oceans, the atmosphere, and the weather.  Remember that all of these subjects are related and your lectures should reflect this.
      

  2. Discuss with students the following major points about water or the hydrologic cycle.  Draw the diagram of the water cycle.

  1. Water precipitates from clouds as rain, snow, sleet, or hail to the Earth’s surface.

  2. Depending on a number of factors such as soil type, slope, moisture conditions, and intensity of precipitation will either infiltrate into the ground or runoff into rivers and streams

  3. Virtually no water infiltrates through paved roads and parking lots, so almost all of it becomes   urban runoff.  Runoff from rivers, and streams is stored in large bodies of water such as lakes, estuaries, and oceans.

  4. Water is returned to the atmosphere evaporation from the surface of land or water bodies, or through plants by a process called transpiration.

  5. Clouds are formed by condensation of water vapor that evaporated from the land or oceans.               

 

  1. Hopefully this diagram should be familiar to students and they should be able to tell you about each of the components.  Ask them which are human-made portions of the water cycle? (Reservoir, dams and canals.)  Where does a spring get its water supply?  (Usually from the ground water percolating up.)  Where does water from the mountains wind up?  (The oceans.)  Which is the newest water? (Rain) Oldest? (Oceans.) 

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