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The
Water Cycle
Background
Information
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Summary: The
Water Cycle inquiry is actually five activities in one. In How Can
You Make a Model of the Water Cycle?, students work in teams to create
water cycle models using two-liter bottles. In What Can the Internet Teach
You about the Water Cycle?, students use interactive Internet resources
to introduce water cycle concepts. In What Are the Processes of the Water
Cycle?, students label their water cycle models
in order to make a concrete connection to water cycle processes. In How
Does Water Cycle on the Earth?, students learn the nine major locations
of water on the planet by playing an interactive game. In How Can Pollution
Get into the Water Cycle?, students explore the effect of pollution in
the water cycle by observing a "chemical" as it travels through the
water cycle model. This activity also utilizes the literature integration of A
River Ran Wild by Lynne Cherry. The Family Page
extends this learning to the community by providing families with challenges to
explore at home.
Related
Topics: water, cycles, plants, weather, energy, molecules, pollution, probability,
states of matter
Ohio Academic Standards Alignment: Click here to view content standards alignment to Science for Ohio by grade level.
Classroom
Time Required: five forty-five minute periods plus assessment
Background
Information:
- The Water Cycle.
The phrase water cycle is used to describe the many processes that
transport water in never-ending cycles on the Earth. The water cycle has
four main processes.
- evaporation: the changing of a liquid into a gas
- condensation: the changing of water vapor from a gas to a liquid
- precipitation: the falling of water to the earth as rain, snow,
sleet, or hail
- collection: the pooling of water on the ground in puddles,
streams, lakes, oceans, etc.
Other
processes include:
- transpiration:
the giving off of water vapor by plants
- percolation:
the mixing of water with soil
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Energy.
Just as your body needs energy to climb a mountain, water needs energy to
climb to the clouds. The energy of the sun creates heat upon striking the
Earth. This heat powers evaporation of water. Without the sun's energy,
there would be no water cycle.
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How
Does Water Cycle on the Earth? This activity expands the traditional
concept of the water cycle as a circle of moving moisture that is constantly
evaporating, condensing, precipitating and collecting to include the major
places where the world's water is stored as it journeys through its cycle.
These locations are described below. Words in capitals represent places
water will go from that water location.
- Animals. Animals
need water in order to survive. They receive their water by drinking
it or through the foods they eat. This water will STAY with the animal
for a period of time before it is excreted to the SOIL through waste
or evaporated to the CLOUDS through perspiration and/or respiration.
Notice that the Animals Spinner is weighted
to show the probability for each type of water movement.
- Clouds. Clouds
receive moisture when the heat of the sun evaporates liquid water into
the air. The moisture then cools and condenses onto dust in the atmosphere
to form clouds. Once in cloud form, this water will STAY in the atmosphere
until it precipitates to the ground and collects in GLACIERS, LAKES,
or OCEANS. Notice that the Clouds Spinner
is weighted to show the probability for each type of water movement.
- Glaciers. Glaciers
receive moisture when precipitation from clouds falls in higher altitudes
and freezes. Once in glacier form, water will usually STAY for an extended
period of time before the heat of the sun causes melted water to slowly
enter the GROUNDWATER or travel into a nearby RIVER. Notice that the
Glaciers Spinner is weighted to show
the probability for each type of water movement.
- Groundwater. Groundwater
is water that is below the soil layer in the earth. This water collects
from rivers, lakes, glaciers, and the soil. Once collected, groundwater
will usually STAY in the ground for an extended period of time as gravity
helps it to slowly filter downward. Once reaching the lowest point of
a watershed, groundwater may filter into a LAKE or RIVER. Notice that
the Groundwater Spinner is weighted
to show the probability for each type of water movement.
- Lakes. Lakes are
large bodies of water that collect water primarily through groundwater,
rivers, and precipitation. Once in a lake, water may STAY for a period
of time before evaporating to the CLOUDS, emptying into RIVERS or GROUNDWATER,
or being consumed by ANIMALS. Notice that the Lakes
Spinner is weighted to show the probability for each type of water
movement.
- Oceans. Oceans
are the largest bodies of water on the planet. They cover 3/4 of the
Earth's surface and hold approximately 97% of the world's water. Oceans
receive most of their water from rivers and through precipitation. Once
in an ocean, water will either STAY or evaporate back to the CLOUDS.
Notice that the Oceans Spinner is weighted
to show the probability for each type of water movement.
- Plants. The cells
of plants need water in order to survive. Plants take in water from
the soil. This water will STAY in the plant as it travels up to the
leaves where it evaporates through a process known as transpiration
to the CLOUDS. Notice that the Plants Spinner
is weighted to show the probability for each type of water movement.
- Rivers. Rivers
receive their water primarily from glaciers, lakes, groundwater, and
soil. Once in a river, this water may supply the moisture needs of ANIMALS,
evaporate to CLOUDS, filter into the GROUNDWATER, or STAY as it flows
downward to LAKES or OCEANS. Notice that the Rivers
Spinner is weighted to show the probability for each type of water
movement.
- Soil. Soil receives
its water primarily from precipitation. Once in the soil, water will
usually STAY for a period of time before evaporating to CLOUDS or filtering
into GROUNDWATER, RIVERS, or PLANTS. Notice that the Soil
Spinner is weighted to show the probability for each type of water
movement.
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How
Can Pollution Get into the Water Cycle? Pollution occurs when
too much of something (e.g., fertilizer, manure, chemicals, etc.) is concentrated
in an area, thus overwhelming the Earth's ability to break it down or decompose
it. Picture the looks on your students' faces as they unexpectedly watch
a pollutant entering the ground/drinking water of their water cycle model.
Water pollution is likely to be one of the greatest environmental challenges
of the 21st century. No civilization can sustain itself without clean water,
and no person is outside the water pollution loop. This brief, but powerful,
visual activity is not an in-depth study of water pollution. Rather, it
serves to plant in students the seeds of awareness and stewardship. This
activity truly illustrates the adage "Seeing is believing."
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Physical
vs. Chemical Change. Water cycling is a physical change, not a chemical
change. See the Physical vs Chemical Change
page for a classroom discussion page that compares the characteristics of
physical and chemical change.
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Misconception(s).
- Misconception:
The same water cycles in the same part of the Earth over and over. Fact:
A drop of water could travel to virtually any part of the Earth during
its journey through the water cycle.
- Misconception:
Businesses and industries are responsible for water pollution. Fact:
Water pollution from residential areas via sewage, pesticides, etc.,
is a large source of water pollution.
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Caution(s).
Emphasize the safe use of scissors and other sharp instruments during construction
of water cycle models.
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Expected
Results. Students will learn the processes and functions of the
water cycle, as well as the human role in the Earth's water cycle.