THE
WATER CYCLE
TEACHER'S GUIDE
CONTENTS
All material in this program is the exclusive property of the copyright holder. Copying, transmitting,
or reproducing in any form or by any means
without prior written permission from the copyright
holder is prohibitied (Title 17, U.S. Code Sections
501 and 506.)
©1993 United Learning, Inc.
THE WATER CYCLE
TIME: 10:25 minutes
INTRODUCTION
Water, the essential liquid, makes up all living things and is
used in life and industrial processes. The continuous use
and recycling of water molecules is a fundamental cycle of
nature—The Water Cycle
This program can be used in Grades 5-9.
PROGRAM OBJECTIVES
After viewing the video and participating in various activities, the viewer should be able to achieve the following
objectives:
• compare the earth's waters—salt and fresh in regard to
quantity, quality, and usability
• define evaporation
• define transpiration
•
describe the movement of water molecules from the
earth's surface into the atmosphere and back down
again
• define precipitation
•
trace the path of water molecules through the water
cycle starting from a local body of water
-1-
recycled through nature. This allows them to be used
over and over again.
describe the purification aspect of the water cycle
PRESENT THE VIDEO • Time: 10:25 minutes
SUMMARY OF THE VIDEO
The video dramatically presents water—its commonness,
importance, and uses. The abundance of water, but the
relative scarcity of usable water, is emphasized. The water
cycle, its efficiency and importance are presented.
FOLLOW-UP ACTIVITIES
1.
Blackline Master 2 is a concept map dealing with
water, its composition, and forms. The students are
to fill in the boxes using words from the list on the
page. The connecting words will help to form meaningful sequential sentences. Concept maps may be
utilized in different ways. They may be completed by
individuals in or out of class, or used in a group. They
may serve as a basis for class discussion.
2.
Blackline Master 3 is a concept map dealing with
fresh water, its availability and uses.
TEACHER PREPARATION
1. Preview the video and read this guide to determine
how best to present this program to your class.
2. Preview the blackline masters and duplicate the ones
you intend to use.
INTRODUCING THE VIDEO
1. Blackline Master 1, "Vocabulary," could be used as
a basis for class discussion and/or review prior to the
A/V presentation. This will help you determine how
much your students know about the water cycle before
viewing the video.
2. Explain to the students that this program emphasizes
two key points:
a. Water is a key resource.
b.
What we see is what we've got: The water on
earth today is all we will ever have. No new water
is created.
It then goes on to point out how water molecules are
-2-
3. Blackline Master 4 is a concept map dealing with the
water cycle.
4.
Blackline Master 5 is a concept map dealing with
evaporation, its role in the water cycle and purification.
5. Blackline Master 6 is a diagram of the water cycle.
Students are asked to write a short essay interpreting
the diagram.
6. Blackline Master 7 is a list of questions that may be
used as a quiz, assignment, or basis for discussion.
DISCUSSION
1. Nature conserves precious resources by recycling
them. This allows them to be used over and over
-3-
2.
again. Discuss the nature of recycling and mention
other examples. How is recycling and the concept of
cycles related?
meter. A water bill will show the consumption for a
given period.
The fresh water on the earth's surface is in limited
quantity and unequally distributed. What measures
have and are being used to deal with shortages and
problems? The world's population is increasing, but
the supply of fresh water is not. What possible
measures might be considered in regard to future
problems?
ANSWER KEY
3. Every time you flush a toilet you are using fresh water
and polluting it. The addition of any wastes and
chemicals pollutes water and renders it unfit for other
uses, especially drinking. How is polluted water
purified by human efforts and nature?
4.
Blackline Master 1, "Vocabulary."
Vocabulary Sheet for distribution and discussion.
Blackline Master 2, "Water - Concept Map."
Excesses and shortages of water, floods and
droughts, are common. What problems and damage
result? What measures have been undertaken to
cope with such water problems and their effects? Are
new solutions possible? What?
PROJECTS
1.
Weather is often big news. Rainfall is at times too
much or too little. The measurement of rainfall by
means of an inexpensive rain gauge may be made
and recorded. The accuracy of forecasts and predictions could be evaluated.
2. Water costs money! For many, the price is rising. How
much does your family pay for water? It would be
interesting and surprising to determine how much
water your family uses in one day, one week. This
could be done by recording the numbers from a water
-4-
-5-
Blackline Master 3, "Fresh Water - Concept Map."
-6-
-7-
Blackline Master 6, "The Water Cycle."
Answers will vary but should contain some of the following:
The movement of water between the ground and the
atmosphere is called the water cycle. When the sun shines
on bodies of water, the sun's energy changes some of the
water into water vapor. This is called evaporation. Plants
are another major source of water vapor as they pass water
out through tiny holes in their leaves—a process called
transpiration. Winds carry the water vapor through the air.
When the air cools, the water vapor condenses into little
drops of water. This is called condensation. Clouds form.
The water in the clouds falls to the ground as rain, snow,
etc. This is called precipitation. The sun shines and the cycle
starts again.
When the sun shines on bodies of water and plants
the heat causes evaporation and transpiration from
the plants creating water vapor that rises, condenses
into forms of water and falls to the earth as
precipitation.
Blackline Master 7, "Quiz/Discussion"
Answers will vary, but should contain the following:
1. Evaporation is the change in physical state to a gas or
vapor—usually the change in water from a liquid into
the gas called water vapor. Its role is the movement
of water molecules from the earth's surface into the
atmosphere.
2. Salt and pollutants are left behind as water molecules
move from a body of water into the air as water vapor.
3. Transpiration occurs when plants pass water, in the
form of water vapor, out into the atmosphere through
tiny holes in their leaves.
4. Water vapor is water in a gaseous state.
-8-
-9-
SCRIPT OF VIDEO PRESENTATION
Water...of all the many different substances around us, none
is more important; none more vital to our survival. Without
water there can be no life, no farms on which to grow our
food, no cities or towns, no anything in fact but the bare,
base rock from which our planet is made.
At first glance it might seem that, when it comes to water,
we're in great shape—that there's more than enough to
meet our many needs for it. Seen from space, the earth
looks to be awash with water which, in fact, it is, with more
than 70 percent of its surface covered with oceans, seas,
bays, lakes, and other such bodies of water. There is,
however, one serious problem with most of this water as far
as we humans are concerned. It's the wrong kind. It's salt
water. Now that may be just fine for the fish and other
organisms that live in it, but it doesn't do us humans much
direct good. We're different. We need fresh water—fresh,
salt-free water to drink, to run our businesses and industries, and to irrigate our crops. And we need lots of it.
The amount of fresh water we need for even the simplest
tasks is truly amazing. Take, for example, that morning
shower. Just five minutes or so in it can use 25 gallons or
better of the hundred or more gallons of fresh water each of
us uses around our home every day. And then there's
breakfast. Well, believe it or not, every egg we eat takes
about 125 gallons of fresh water to produce. Then, how
about watering the lawn for five minutes or so? Well, that
will use up another 50 gallons or more of fresh water. And
then, you're off in your car—a car that took some 100,000
gallons of water to manufacture, plus another 30,000
gallons or so to make its four tires. So, as you can see,
these, and all our many other uses for it, add up quickly to
the need for lots and lots of fresh water.
-11-
And just where does all this fresh water—all the millions and
millions of gallons we need—come from? Well, the world's
oceans are no direct help. True, they do contain nearly all
the earth's water supply. But, as we said earlier, ocean
water is the wrong kind of water for us. It's salt water, water
we can't drink, water we can't use to irrigate our crops. The
truth is that only a tiny part of the world's water, only about
three percent of it, is fresh water, the kind we so desperately
need. And most of this—some two-thirds of it in fact—isn't
available because it's locked up in glaciers, ice caps, or deep
underground. That leaves less than one percent—less than
one-hundredth of the water on the planet—to take care of all
the world's many needs for fresh water. And on top of that,
the water we have today is all we'll ever have—or, for that
matter, all the earth ever had. That's because, for all
practical purposes, no new water is ever created. The water
that's with us today is all there ever will be.
So, as you can see, when it comes to water, it's definitely a
case of "what we see is what we've got." It's that simple.
Obviously then, it so little fresh water is available, and if
what there is is so very important to us and so many other
organisms, what happens to the world's fresh water supply is
all important. And that brings up an interesting question. If
there's so little fresh water available, just how is it that the
earth didn't run out long ago? How, considering all its many
uses, is it that there's any left today?
The answer is recycling. The earth's water supply is
naturally recycled, naturally used and reused. Thus, water
molecules are used time and time again as they have been
since early on in our planet's long history. We call this
natural recycling process "the water cycle," and, in its
simplest form, it involves the movement of water molecules
from oceans and other sources up into the atmosphere
where many of them clump together to form clouds. Later,
these water molecules fall back to earth as rain, snow, or
-12-
some other precipitation. Finally, they flow into streams and
rivers for their return trip to the ocean where the cycle began
and will begin again.
Like every other system, the water cycle needs energy to
keep it running. This energy comes from the sun. The sun's
energy warms the earth's oceans, rivers, lakes, and other
waters. It's this solar heating that causes water molecules, in
the form of invisible water vapor, to evaporate up into the
atmosphere. This sun-powered evaporation also works as a
natural distillation process, leaving the salts in the ocean
water behind, thus replenishing the world's fresh water
supply.
But the world's oceans and other bodies of water aren't the
only source of atmospheric water. Evaporation from wet
soil also adds waterto the atmosphere, as do plants. Plants
take in water from the soil in which they grow. Later, some of
it, in the form of water vapor, passes out of the plants
through tiny holes in their leaves. Called transpiration, this
process adds huge amounts of water to the atmosphere.
Trees, for example, can give off hundreds of gallons of
water a day. But, if you think that's a lot, here's a source of
far more—a corn field. Believe it or not, an acre of corn can
pump 4,000 or more gallons of water a day up into the
atmosphere.
So far, we've examined the water cycle's up side—the
evaporation that takes place from oceans and other bodies of
water, and transpiration from plants. But, as we all know,
what goes up comes back down. This return trip begins as
clouds form when the water vapor in the atmosphere cools
and condenses into tiny drops of liquid water. Over time,
this falls back to earth as rain or some other precipitation.
Most of it falls into the world's oceans, rivers, lakes, and
other such bodies of water. The rest falls on land. Some of
this immediately evaporates back up into the atmosphere.
Much of the rest runs into streams and rivers, after
-13-
time flowing back to the sea. Other precipitation soaks into
the ground and becomes part of the ground-water supply.
Eventually, much of this seeps underground into streams
and rivers, thus joining them for their return trip to the sea.
With this return to the ocean, the water cycle—that neverending circulation of the earth's water supply—is complete
and ready to begin again, as it always has and always will.
-14-
Name___________________
THE WATER CYCLE
VOCABULARY
Condensation: changing of a gas or vapor into a liquid.
Cycle: a periodically repeated sequence of events; a series of events or operations that
repeat regularly in the same order.
Evaporation: the act of changing a liquid into a vapor or gas.
Fresh water: the water found in lakes, rivers, and underground deposits, possessing little
salt in contrast to the salt water of oceans and seas.
Precipitation: falling products of condensation in the atmosphere, as rain, snow, hail.
Purification: being made pure, not mixed with anything else.
Recycle: to use a material more than once. Transpiration: the
loss of water vapor from a plant.
Water: the liquid which in a more or less impure state constitutes rain, lakes, rivers, and
oceans. In its pure state it is a colorless, odorless, and tasteless liquid. It is a compound
composed of oxygen and hydrogen.
Water Vapor: water in a gaseous state.
The Water Cycle
©1993 United Learning, Inc.
2
Name___________________
THE WATER CYCLE
WATER - CONCEPT MAP
Directions: Fill in the boxes with words from the list on this page.
The Water Cycle
©1993 United Learning, Inc.
3
Name___________________
THE WATER CYCLE
FRESH WATER - CONCEPT MAP
Directions: Fill in the boxes with words from the list on this page.
The Water Cycle
©1993 United Learning, Inc.
4
Name___________________
THE WATER CYCLE
THE WATER CYCLE - CONCEPT MAP
Directions: Fill in the boxes with words from the list on this page.
The Water Cycle
©1993 United Learning, Inc.
Name__________________
THE WATER CYCLE
EVAPORATION - CONCEPT MAP
Directions: Fill in the boxes with words from the list on this page.
The Water Cycle
©1993 United Learning, Inc.
6
Name____________________
THE WATER CYCLE
INTERPRET THE DIAGRAM
Directions: Interpret the diagram below and write an explanation on how the water cycle
works. Use the back of this activity sheet.
The Water Cycle
©1993 United Learning, Inc.
Name__________________
7
THE WATER CYCLE
QUIZ/DISCUSSION QUESTIONS
1. Define evaporation. What role does it play in the water cycle?
2. How is water purified in the water cycle?
3. What is transpiration?
4. Define water vapor.
5. Briefly describe the water cycle.
The Water Cycle
©1993 United Learning, Inc.