Water Cycle - Water (3)
Pre Lab 

  • Exploring the movement of water.
  • Comparing the different components of the water cycle.
  • condensation
  • evaporation
  • ground water
  • reservoir
  • water cycle
  • worksheet 

Students use a worksheet to trace the water cycle.


The hydrologic or water cycle is a major driving force on our planet.  Water is in constant motion, evaporating into the atmosphere to and from oceans, lakes, rivers, and streams.  When the atmosphere can no longer support the moisture within the clouds we experience rain, snow, hail, or sleet.  Some water  is locked in the form of ice at the polar caps and in  glaciers. Water is returned to the system through drainage, which results from the melting of snow that has accumulated during the winter months.  This water flows on the surface of the Earth and percolates through the Earth as groundwater. Water is not actually consumed but is continuously recycled.    When water is heated, it changes from the  liquid to the gas water vapor.  This process is called evaporation.  When water vapor is cooled, as it would be if it were taken higher in the atmosphere, this gas will condense, or change back to liquid form.

We can see water vapor condensing when we watch clouds.  A cloud is nothing more than water vapor that has condensed back to a liquid form.  A cloud is made of extremely tiny drops of water which can remain suspended in the air. A cloud is a colloid, or 2 states of matter (liquid and air).  As a cloud grows, and more and more water condense in the same place, the cloud droplets get larger.  Eventually, these cloud droplets will be too large to remain in the air.  The cloud is then said to be saturated.  A saturated cloud will usually precipitate its excess water, or cause it to fall.  This is how it rains or snows.  Moisture falling from clouds is called precipitation.

The cycle of evaporation, condensation, and precipitation of water is called the water or hydrologic cycle.   Since clouds move across the sky, the precipitation does not usually fall in the same place that the water came from.  This is how the Earth spreads water across land areas and allows us to live in so many different areas.

  1. Using the enclosed diagram, students should trace the movement of water through the water cycle as well as find places where water can be stored and generated.  Ask students if they think that snow produces a lot of or a little of water.  They may be amazed that 10 inches of snow is required for 1 inch of rain.  
  2. Have them notice that some water is trapped under the Earth and then emerges as springs.  In this diagram, man-made features are illustrated to capture water, like reservoirs and dams.  
  3. Below is a  diagram of the movements that students should be able to trace.  Slowly go over each of the steps of  the water cycle.  See how much material they remember from previous grades.  Make sure the students understand each of the vocabulary words.

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