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Water Cycle

delta science modules Water Cycle 123

Water Cycle

In the Delta Science Reader Water Cycle,students read about why Earth is called thewater planet. They find out about salt waterand fresh water and where each kind ofwater is found. They observe how waterchanges form by freezing, melting,evaporating, and condensing. They trace thewater cycle and find out how heat energyfrom the sun is related to the water cycle.They learn how Earth’s weather is affectedby the water cycle. They also read aboutLuke Howard, the scientist who firstclassified clouds. Finally, studentsinvestigate water as a natural resource.

Students will

� find out that almost three-fourths of Earth’ssurface is covered by water and that mostof Earth’s water is the salt water in oceansand seas

� discover that fresh water is found onEarth’s surface, in the ground, in plants,and in the atmosphere

� understand the relationship betweentemperature and how water changes formthrough freezing, melting, evaporation, andcondensation

� learn the stages of the water cycle and therole that it plays in the weather

� examine nonfiction text elements such astable of contents, headings, and glossary

� interpret photographs and diagrams toanswer questions

� complete a KWL chart

Reader

DeltaScience

Delta Science Readers are nonfiction student

books that provide science background and

support the experiences of hands-on activities.

Every Delta Science Reader has three main

sections: Think About . . . , People in Science,

and Did You Know?

Be sure to preview the reader Overview Chart

on page 4, the reader itself, and the teaching

suggestions on the following pages. This

information will help you determine how to

plan your schedule for reader selections and

activity sessions.

Reading for information is a key literacy skill.

Use the following ideas as appropriate for your

teaching style and the needs of your students.

The After Reading section includes an assessment

and writing links.

OVERVIEW

© Delta Education LLC. All rights reserved. Permission to reprint for classroom use only.

READING IN THE CONTENT AREA SKILLS

• Make and confirm predictions aboutsources of fresh water

• Identify cause-and-effect relationshipsrelated to water’s changes of state

• Compare and contrast the states of matterin which water can be found

• Identify main ideas and supporting detailsin text sections

• Describe the sequence of events in themovement of water through plants

• Demonstrate critical thinking• Interpret graphic devices• Summarize

NONFICTION TEXT ELEMENTS

Water Cycle includes a table of contents,headings, photographs, illustrations, captions,boldfaced terms, diagrams, maps, labels, achart, and a glossary.

CONTENT VOCABULARY

The following terms are introduced in contextand defined in the glossary: absorb,atmosphere, cloud, condensation,desalination, estuary, evaporation, freeze,glacier, groundwater, humidity, iceberg, ice cap, irrigation, lake, melt, ocean,photosynthesis, porous, precipitation,resource, river, runoff, surface water,transpiration, water conservation, water cycle,water table, water treatment plant, watervapor, weather.

Optional vocabulary: nonrenewable resource,renewable resource

Build Background

Access students’ prior knowledge of the watercycle by displaying and discussing the cover.Ask, What do you see in this picture? (water,a lake, a shoreline with plants, ocean) Whateffects do you think bodies of water suchas this have on our everyday lives? (Acceptreasonable responses.)

Read the title aloud, and invite students toshare what they know about the topic fromtheir personal experiences and hands-onexplorations in science. To stimulatediscussion, ask questions such as these:What is rain? What do you think causesrain? Where does the water in rain comefrom? Where can we find water? What aresome ways that water changes?

Begin a group KWL chart by recording factsstudents know about the water cycle in the Kcolumn and questions students have aboutthe water cycle in the W column. You maywant students to copy the KWL chart so theycan maintain their own charts as they read.

Preview the Book

Explain that when students previewnonfiction, they should look at the title, thetable of contents, headings, boldfaced words,photographs, illustrations, charts, graphics,and captions.

Then preview the book with students. Callattention to the various nonfiction textelements and explain how they can helpstudents understand and organize what they

124 delta science reader

BEFORE READING

KWhat

I Know

WWhat

I Want

to Know

LWhat

I Learned

+What

I Want to

Explore

Further

© Delta Education LLC. All rights reserved.


read. Ask questions such as these: How dothe headings help you predict what you willread about? What do you see in thispicture? How do you think it will help youunderstand the text? Explain that the wordsin boldface type are important words relatedto the water cycle. Point out that these wordsare defined in the glossary. Choose one wordand have students find its definition in theglossary.

Preview the Vocabulary

You may wish to preview some of thevocabulary words before reading, rather thanwaiting to introduce them in the context ofthe book. Possibilities include creating a wordwall, vocabulary cards, sentence strips, or aconcept web.

For example, some of the words can becategorized in multiple ways. With students,develop a word web such as the following.

Set a Purpose

Discuss with students what they might expectto find out from the book, based on theirpreview. Encourage them to use the questionson the KWL chart to set an overall purpose for reading.

Preview the book yourself to determine theamount of guidance you will need to give foreach section. Depending on your scheduleand the needs of your class, you may wish toconsider the following options:

• Whole Group Reading Read the bookaloud with a group or the whole class.Encourage students to ask questions andmake comments. Pause as necessary toclarify and assess understanding.

• Shared Reading Have students work inpairs or small groups to read the booktogether. Ask students to pause after eachtext section. Clarify as needed and discussany questions that arise or have beenanswered.

• Independent Reading Some students maybe ready to read independently. Have themrejoin the class for discussion of the book.Check understanding by asking students toexplain in their own words what they haveread.

Tips for Reading

• If you spread out the reading over severaldays, begin each session by reviewing theprevious day’s reading and previewingwhat will be read in the upcoming session.

• Begin each text section by reading or havinga volunteer read aloud the heading. Havestudents examine any illustrations orgraphics and read accompanying captionsand labels. Discuss what students expect tolearn, based on the heading, illustrations,and captions.

• Help students locate context clues to themeanings of words in boldface type.Remind them that these words are definedin the glossary. Provide help with wordsthat may be difficult to pronounce.

• As appropriate, model reading strategiesstudents may find helpful for nonfiction:adjust reading rate, ask questions,paraphrase, reread, visualize.

WATER

groundwater

lake river

salt water

oceanfresh water

� Beginning of concept web for water.

GUIDE THE READING


Think About . . . (pages 2–12)

Pages 2, 3 Why Is Earth Called the WaterPlanet? and Salt Water

• Before students read, direct their attentionto the photograph of Earth seen fromspace. Ask, What is the main feature ofEarth that you see? (the oceans) Thenhave students read about the water planet.

• Elicit main ideas about Earth and its water.Ask, What makes Earth the water planet?(Almost three-fourths of its surface iscovered by water.) What is the mostimportant idea—the main idea—youlearned about the importance of water?(Water makes life on our planet possible.)What detail supports this main idea? (Allliving things need water to stay alive andhealthy.) What are some of the ways inwhich we use water? (drinking, cooking,bathing, transportation, electrical power,water sports)

• Have students read the body text on page 3 and look at the photographs andcaptions on pages 2 and 3. Ask, Whatkind of water covers most of Earth?(salty ocean water) What are the names of Earth’s four main oceans? (Pacific,Atlantic, Indian, Arctic) Direct attention tothe map and guide students to recognizethat the oceans are all connected.

• Ask, What is the most interesting orsurprising fact you learned about saltwater? (Responses will vary, but studentsmay mention the existence of saltwaterlakes as a surprising fact.)

• If necessary, provide help with thepronunciation of estuary (ES-chew-air-ee).

Fresh Water on Earth’s Surface

• Have students read page 4 to learn aboutEarth’s surface water. Ask, Where is mostof Earth’s fresh water? (frozen in glaciers,ice caps, and ice sheets) You might wantto tell students that scientists estimatethat if all of the ice in the glaciers and icecaps melted, the sea level would rise by

about 80 meters (about 260 feet). Pointout that water frozen in ice caps is notavailable to us, but people have beenworking on ways to harvest icebergs fortheir water.

• Have students study the diagram at thebottom of page 4 and read the caption.Ask, Are you surprised to learn how littlefresh water there is on Earth’s surface?Why or why not? (Responses will vary.)Encourage students to predict where elsefresh water might be found.

• If necessary, provide help with thepronunciation of glacier (GLAY-shur).

Page 5 Fresh Water in the Ground

• Before reading page 5, ask studentswhether any of them predicted that freshwater could be found in the ground. Havethem confirm their predictions by readingthe text about groundwater and studyingthe diagram.

• Ask, How does water get into the ground?(Water from rain and melting snow and iceseeps into the soil and fills air spaces insoil and rock.) What are soils and rocksthat can absorb water called? (porous)Point out that the word porous comes from pore, which means “opening.” Havestudents explain what the water table is.(Water spreads out in soil and rock and fillsall the air spaces. The top level of thatwater is called the water table.)

• Encourage students to speculate aboutwhat happens to the water table inperiods when there is very little rain orsnow. (It gets lower.)

• If necessary, provide help with thepronunciation of porous (POR-us).

Page 6 Fresh Water in Plants

• Before students read page 6, ask, Did youpredict that plants are a place wherefresh water is stored? Have students readto confirm their predictions. Remind them

126 delta science reader© Delta Education LLC. All rights reserved.


to study the diagram to help themunderstand the text.

• After reading, ask, How do plants usewater? (Water moves minerals and storedfood to all parts of a plant. Plants mixwater with carbon dioxide to make theirown food.) What happens when plants donot get enough water? (They wilt and die.)

• To test understanding, ask students todescribe the sequence of events in themovement of water through a plant.(Groundwater is absorbed into the roots.It travels up the trunk or stem and into the leaves. There, water is used inphotosynthesis to make food for the plant.Water that is not used by the plant goesinto the air through tiny holes in theleaves.) What is this movement of water from a plant into the air called?(transpiration) How did the diagram helpyou understand the text? (It shows inpicture form what the text explains withwords.)

• If necessary, provide help with thepronunciation of chlorophyll (KLOR-uh-fil),photosynthesis (fo-to-SIN-thuh-sis), andtranspiration (tran-spuh-RAY-shuhn).

Page 7 Fresh Water in the Atmosphere

• Before having students read page 7, askwhether anyone predicted that some freshwater is found in the atmosphere, or air.Invite students to read page 7 to confirmtheir predictions.

• Check comprehension by asking, Whattwo forms does water in the atmospheretake? (One form is as a gas called watervapor. The other form is as water dropletsor ice crystals in clouds.) Which of theseforms can we see? Which are we unableto see? (We can see clouds, but we cannotsee water vapor.)

• Ask, What is humidity? (a measure of theamount of water vapor in the air) Howwould you describe the humidity today?Would you say that it is high or low?

(Responses will vary.) What do you thinkcauses the humidity to change? (Acceptall ideas.) Explain that the amount ofwater vapor in the air changes with thetemperature. More water evaporates intothe air when it is warm, and more watercondenses out of the air when it is cool.

• If necessary, provide help with thepronunciation of atmosphere (AT-muh-sfeer), humidity (hew-MID-ih-tee), andhygrometer (hi-GROM-uh-ter).

Pages 8, 9 How Water Changes Form

• Have students read the text about states ofmatter in the first column on page 8 andlook at the accompanying photographs andlabels. Check comprehension by havingstudents summarize the information. (Thethree states of matter are solid, liquid, andgas. A solid has a shape of its own; a liquidand a gas do not. Ice is the solid form ofwater, water is the liquid form, and watervapor is the gas form.) Guide students tocompare and contrast the three states ofmatter of water. Ask, How are ice, water,and water vapor alike? (They are all formsof water.) How are they different? (Ice hasits own shape. Water and water vapor haveno shape of their own. We can see waterand ice, but we cannot see water vapor.)

• Then have students read through the endof page 9 to discover how water changesform. Ask, What causes water to changeform? (adding or taking away heat energy)What happens when enough heat energyis taken away from a liquid—water? (Itbecomes a solid—ice.) What causes asolid such as ice to turn back into aliquid? (adding heat) What is this processcalled? (melting) What is the effect ofadding more heat to a liquid? (The liquidchanges into a gas. Water becomes watervapor.) What is this process called?(evaporation) What causes water vapor toturn back into a liquid? (taking heat away;cooling it) What is this process called?(condensation) Discuss the examples ofeach process shown in the photographs.


• You may wish to tell students about twoother changes of state for water: frostformation occurs when water changesdirectly from a gas to a solid, andsublimation is the direct change from solid to gas.

• If necessary, provide help with thepronunciation of evaporation (ih-vap-uh-RAY-shuhn).

Pages 10, 11 What Is the Water Cycle?

• Before students read pages 10 and 11,write the word cycle on the board. Explain:The words cycle and circle are related.Just as you can run your finger aroundand around a circle, a cycle repeatsitself in the same order. Brainstorm someother terms or words that contain cycle.(Students may suggest bicycle, tricycle,life cycle, cyclone.) Then ask, What doyou think the water cycle might be?Before they answer, tell students to thinkabout what they learned about how waterchanges form and what causes thesechanges. (Accept reasonable responses.)

• Have students examine the diagram andread the caption and labels to confirm theirideas about the water cycle. Ask, Howdoes water from Earth’s surface get intothe air? (It evaporates.) What happens towater vapor in the air? (It condenses andforms clouds.) What do you see fallingfrom the clouds? (rain) Where does therain go? (It falls back down to Earth’ssurface and into the ground.)

• Then have students read the text on page 10 to determine what causes thiscycle to take place. Ask, What is thewater cycle? (the movement of waterbetween Earth and the atmosphere andback again) To check comprehension ofthe water cycle, elicit the cause-and-effectsequence. Ask, What causes the watercycle to begin? (Heat energy from the sunwarms Earth’s water and causes it toevaporate.) What happens to warm air inthe atmosphere? (It cools and condensesback into water.) What is the effect of

condensation? (Clouds form.) Whatcauses the clouds to release their water? (The water droplets get larger and heavier.) What happens to theprecipitation? (It returns to Earth,becomes surface water and groundwater,and the cycle starts again.)

• Ask whether students were surprised tolearn that the same water continuallymoves through the water cycle betweenEarth and the atmosphere. Invite studentsto explain why they were or were notsurprised. Point out that the water we usetoday is the same water that has been onEarth since the oceans were formed on theplanet several billion years ago. It allpasses through the water cycle over andover again. Every day 1 trillion tons ofwater move through the water cycle.

• Students may be interested to know thatthe water cycle was first suggested some2,500 years ago by a Greek scientist,Thales of Miletus (c. 625–550 B.C.E.)

• If necessary, provide help with thepronunciation of precipitation (prih-sip-ih-TAY-shuhn).

Page 12 Earth’s Weather

• Have students read page 12 to discoverhow the water cycle affects the weather.Check comprehension by having studentsexplain what causes changes in theatmosphere. (the heating and cooling ofthe land, water, and air) Ask, How dothese changes affect the weather? (Theycause changes in the temperature and inthe amount of water vapor in the air. Theyaffect cloud formation and precipitation.)

• Have students look at the photographsand read the captions. Ask, What causesrain to fall? (Water droplets become toobig and heavy to stay in the air.) Whatcauses snow to fall instead of rain?(Cold temperatures keep the ice crystalsthat fall from clouds frozen all the way tothe ground.) What is fog? (a cloud that isclose to the ground)



• If appropriate, discuss the differencebetween weather and climate. Explain thatweather refers to day-to-day conditions,such as rain, sunshine, wind, and snow.Climate refers to the average weatherconditions in an area over a long periodof time.

People in Science (page 13)

Luke Howard

• Before they read, access students’ priorknowledge of clouds. Invite volunteers toshare what they know about the differenttypes of clouds and their names. Havestudents study the cloud photographs andread the captions. You may wish to havestudents look out the window to determinethe types of clouds—if any—that are in thesky and what kind of weather they are aclue to. Then have students read page 13to learn about the man who first namedand classified clouds.

• Students may be interested to know thatbefore 1800, clouds were often describedas only “essences” floating in the sky. Theirnature and causes were not understood.Ask, What conclusions can you draw fromthe fact that Howard’s system is still inuse today? (Students may suggest that it isa useful system or that no better systemhas been suggested.)

• If necessary, provide help with thepronunciation of cirrus (SEER-us), cumulus(KEW-myuh-lus), and stratus (STRAT-us).

Further Facts

• Luke Howard is regarded as the father ofmeteorology, the science that deals withthe atmosphere, especially the weather.

• Howard’s interest in the skies wasstimulated by the brilliant sunrises andsunsets and incredible skies of 1783,when he was eleven. Violent volcaniceruptions in Iceland and Japan had sentclouds of dust and ash into the air,causing unusual atmospheric effects in

the Northern Hemisphere that lasted fromMay through August.

• Howard kept a daily record of hismeteorological observations for more thanthirty years.

• “Notes on the Modifications of theClouds,” in which Howard presented his cloud classification system, wasillustrated with Howard’s own watercolorswhen it was published in 1803. Many ofHoward’s sketches can be viewed online.

• Howard later added a fourth category ofclouds—nimbus (the Latin word for“rain”)—to identify clouds from which rainwas falling.

Did You Know? (pages 14–15)

Water Is a Resource

• Before they read pages 14–15, invitestudents to guess how much water theaverage person in the United States useseach day. Record guesses on the board.Then have students read to find out aboutwater as a resource.

• After they read, ask, Other thanhousehold use, in what ways is water anatural resource? (Dams change energyfrom moving water into electricity; water isused for irrigation on farms; most drinkingwater comes from groundwater; manyfoods we eat, such as fish and shellfish,live in water.)

• Ask, How do people affect our watersupply, according to the text? (Water canbe polluted by chemicals and fertilizers.Paved areas prevent water from enteringthe groundwater, which lowers the watertable.) You may wish to discuss otherways water is affected by people’s actions,such as these: Evaporation behind damsadds water vapor to the atmosphere.Irrigation canals divert water from oneplace to another, causing drought wherethe water once flowed naturally. Wellslower the water table.


• You may wish to introduce the concept ofrenewable and nonrenewable resources.Renewable resources are resources that are either available in unlimited supply orthat are constantly being replaced orreplenished. The sun and wind are limitlessrenewable resources; forests are arenewable resource that can be replaced.Nonrenewable resources cannot bereplaced once they are used. Coal, oil, andnatural gas are examples of such resources.They will eventually be used up. Askstudents which kind of resource they thinkwater is and why. (Water is a renewableresource; water keeps moving through thewater cycle being used again and again.)

• Discuss the chart of water use withstudents. Encourage students to sharetheir reactions to the amounts of waterused for each activity and the estimateddaily use presented on page 15. Stimulatediscussion by asking questions such asthese: What is the most surprising factyou learned about water use? Willknowing this information change theway you use water? What changes canyou make to use less water?

• If necessary, provide help with thepronunciation of desalination (de-sal-ih-NAY-shuhn).

Summarize

Complete the KWL chart you began withstudents before reading by asking them toshare the answers to their questions. Call onvolunteers to retell each text section. Thenhave students use the information in the KWLchart to write brief summary statements.

Discuss with students how using the KWLstrategy helped them understand andappreciate the book. Encourage them toshare any other reading strategies thathelped them understand what they read.

Direct attention to the fourth column in thechart and ask, What questions do you still

have about the water cycle? What wouldyou like to explore further? Record students’responses. Then ask, Where do you thinkyou might be able to find this information?(Students might mention an encyclopedia,science books, and the Internet.) Encouragestudents to conduct further research.

Review/Assess

Use the questions that follow as the basis fora discussion of the book or for a written ororal assessment.

1. What are the two kinds of water on Earth?(salt water, fresh water) Where is each typefound? (Salt water is found in oceans andsaltwater lakes. Fresh water is found inglaciers, ice caps, lakes, ponds, rivers, theground, plants, and the atmosphere.)

2. What are the three states of matter ofwater? (ice, a solid; water, a liquid; andwater vapor, a gas) How does water changestate? (Water changes state when heat isadded or removed. Heating solid ice causesit to melt and change to a liquid. Heatingliquid water causes it to evaporate to a gas.Cooling water vapor makes it condense to aliquid. Cooling liquid water to the freezingpoint makes it freeze to solid ice.)

3. How does the water cycle affect theweather? (Changes in the water cycle causechanges in the atmosphere. This causeschanges in the weather, such as theamount of clouds or precipitation.)

Writing Links/Critical Thinking

Present the following as writing assignments.

1. Describe the stages in the water cycle, andtell why the water cycle is important. (Wateron Earth is warmed by the sun and turnsinto water vapor. In the air, water vaporcondenses and forms clouds. Water dropletsin clouds fall to Earth as precipitation. Thenthe cycle starts again. Students’ ideas aboutthe importance of the water cycle will varybut should include that it allows us to usethe same water over and over and that itaffects Earth’s weather.)

AFTER READING



2. Luke Howard studied something otherpeople had not thought worth studying—clouds. As a result, he made importantdiscoveries about the relationship betweenclouds and weather. If you could spendtime studying something other people havenot paid much attention to, what wouldyou choose? Why? (Responses will vary.)

Science Journals: You may wish to havestudents keep the writing activities related tothe Delta Science Reader in their sciencejournals.

References and Resources

For trade book suggestions and Internet sites,see the References and Resources section ofthis teacher’s guide.


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