Home-School ConnectionHome-School Connection

(fol

d he

re)

© M

acm

illan

/McG

raw

-Hill

Name

Word WorkoutWORDS TO KNOW

brittle current eventually

reef suburbs partnership

Silly Stories Let’s make up a silly story with the words. For example, we could tell of a coral reef gobbling up a town.

SPELLING WORDS

grocer singer zipper harbor grader

enter powder elevator polar odor

danger tanker collar daughter popular

victor pepper anchor cheddar barber

er, ar, or or? All the spelling words this week have the same ending sound, but the sounds are spelled differently. I’ll write the spelling words, leaving off the last two letters of each word. You can write in the correct ending. We’ll go over your words together.

333

Dear Family Member:Did you know that a coral reef is a living thing?

It is made up of millions of tiny animals called coral polyps. We’re reading about the coral reef this week in At Home in the Coral Reef. I’m reading about all the animals and plants that live in this environment. As I read, I’ll be able to compare the coral reef with other sea environments. I’ll learn how they are alike and different.

This Week’s Skills

Comprehension: compare and contrast

Vocabulary: context clues —multiple-meaning words

Spelling/Phonics: pronouncing er, ar, and or at the end of words

You, the Illustrator Try your hand at illustrating. Choose two different animals or plants. Draw them as best you can. If you are able, add labels. Show your illustrations to a family member. Tell how they are different and alike.

334

© M

acm

illan

/McG

raw

-Hill

Conexión con el hogarConexión con el hogar

(fol

d he

re)

© M

acm

illan

/McG

raw

-Hill

Queridos familiares:¿Sabían que un arrecife de coral es algo que

tiene vida? Está formado por millones de animalitos pequeños llamados pólipos de coral. Esta semana estamos leyendo sobre los arrecifes de coral en un libro llamado At Home in the Coral Reef. Estoy leyendo sobre todas las plantas y animales que viven en este medio ambiente. A medida que lea podré comparar el arrecife de coral con otros ambientes marinos. Aprenderé en qué se parecen y cómo se diferencian.

Destrezas de la semanaComprensión: comparar y contrastar

Vocabulario: claves de contexto —palabras con varios signifi cados

Ortografía/Fonética: la pronunciación de er, ar y or al fi nal de palabra

Nombre

Ejercicio de palabrasPALABRAS DE VOCABULARIO

brittle current eventually

reef suburbs partnership

Cuento fantástico Vamos a inventar un cuento fantástico con las palabras. Podríamos hablar sobre un arrecife de coral que se traga un pueblo entero.

PALABRAS DE ORTOGRAFÍA

grocer singer zipper harbor grader

enter powder elevator polar odor

danger tanker collar daughter popular

victor pepper anchor cheddar barber

¿Cómo terminan? Aunque todas las palabras de ortografía de esta semana tienen el mismo sonido fi nal, ese sonido no se escribe igual. Voy a escribir todas las palabras de la lista, pero sin las últimas dos letras. Tú debes escribir la terminación apropiada. Revisaremos las palabras juntos.

335

Tú, ilustrador¿Tienes mano para el dibujo? Intenta hacer de ilustrador. Escoge dos animales o plantas diferentes. Dibújalos lo mejor que puedas. Si quieres, agrega rótulos a las ilustraciones. Muéstraselas a un familiar. Dile en qué se parecen y en qué se diferencian.

336

© M

acm

illan

/McG

raw

-Hill

AlikeDifferentSummarize

Use a Venn diagram to help

you compare and contrast

two of the natural forces that

change Earth’s surfaces. Then

use the completed diagram to help you summarize

the book.

Think and Compare 1. Turn to pages 10-11 of this book. How are

tsunami waves like other waves? How are they

different? (Compare and Contrast)

2. What kinds of changes to Earth’s surface have

you seen? What do you think caused them?

(Apply)

3. Scientists from all over the world continue to

explore changes to the surface of Earth. What

do they hope to learn? How will their research

help us? (Evaluate/Synthesize)

Comprehension Check

20

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Chapter 1Shifts in the Land. . . . . . . . . . . . . . . . . . . . . . . . 4

Chapter 2Changes Due to Water . . . . . . . . . . . . . . . . . . . 9

Chapter 3Changes Due to Weather. . . . . . . . . . . . . . . . 13

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Glossary/Index . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Comprehension Check . . . . . . . . . . . . . . . . . . . 20

by Barbara M. Linde

Changing Changing Earth Earth

© M

ac

mill

an

/Mc

Gra

w-H

illC

ha

ng

ing

Ea

rth

IntroductionHave you ever seen photographs of Earth

taken from outer space? Earth looks about

the same in all of them. It’s always round.

You always see land and water. From far

away, you’d think that Earth does not change

very much. But that is not true.

In fact, Earth is always changing. Waves

and weather change Earth’s surface. The

land moves and causes changes. Old

features disappear, and new features form.

Earthquakes, volcanoes, and hurricanes are

natural disasters. They change Earth’s surface.

In this book you’ll find out more about the

forces that change the surface of Earth. You’ll

learn how these changes affect Earth.

Earthquakes, landslides, and volcanoes

change the surface of Earth.

2

deposition (dep-uh-ZIH-shuhn) the addition of

material to a landform (page 8)

earthquake (URTH-kwayk) the movement of one or

more of Earth’s plates (page 4)

erosion (i-ROH-zhuhn) a wearing or washing away

over time (page 6)

glacier (GLAY-shuhr) a large body of ice formed by

built-up ice and snow (page 6)

hurricane (HUR-i-kayn) a storm with strong winds,

thunderstorms, and rain (page 15)

tornado (tawr-NAY-doh) a spinning, funnel-shaped

column of wind (page 15)

volcano (vol-KAY-noh) an opening in Earth through

which gases and molten rock erupt (page 5)

Indexcoral, 8

current, 10, 12

delta, 12

deposition, 8, 18

dunes, 16

earthquake, 2, 4, 7, 11

erosion, 6, 7, 16, 18

Florida, 8, 10, 12–15,

glacier, 6

hurricane, 2, 14–15

landslide, 3, 7

rivers, 4, 12

tornado, 14–15

volcano, 2, 5, 7

water cycle, 9

weathering, 17–18

winds, 8, 11, 13, 15–16

Glossary

19

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

ConclusionThe surface of Earth changes all the time.

Waves, weather, and movement shape the

land. Weathering, erosion, and deposition

cause changes. Natural disasters change the

shape of Earth, too. Changes go on every

day. Changes will continue in the future.

Scientists learn more about these changes

all the time. Today they understand the

processes better. They have learned more

about the effects of the changes on the

surface of Earth. You can learn more about

our changing Earth, too. Watch the waves on

a beach. Look at a hillside near your home.

Read more books and magazines about our

fascinating, ever-changing Earth!

18 3

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

C H A P T E R 1

Shifts in the LandEarth’s crust and upper mantle are made

up of large, thin, stiff plates. These plates

border each other. Sometimes one of the

plates shifts and moves against another

plate. This movement causes an earthquake.

Scientists know there are around 20,000

earthquakes every year.

Earthquakes cause changes in the surface

of Earth. Over millions of years, some plates

crashed into each other. The force of the

crashes made parts of the crust rise or fall.

The rising and falling crust formed mountain

ranges. Small or large cracks may suddenly

open up in the ground. The course of a river

can change quickly. Blocks of soil can rush

downward or sideways. Soil under the ground

moves and makes openings on Earth’s surface.

Earthquakes create

cracks called faults.

The San Andreas Fault

is in California. You

can see 625 miles of

the fault on the land.

4

WeatheringWeathering is the breaking up of rock,

wood, soil, and minerals from contact with the

atmosphere. The materials break up or loosen,

but they stay in place. Physical weathering

is a slow process. It is caused by changes

in temperature. Water and ice also cause

physical weathering. Rain may get into cracks

in a rock. The rain might freeze and form ice.

Then the ice expands. The pressure of the ice

may crack the rock even more.

Rocks are made up of different kinds of

minerals. Water and chemicals in the air can

change some of the minerals in the rocks.

Sometimes the rocks change color. Other

times the rocks may slowly break up. This

slow process is called chemical weathering.

Rainwater made the lava very brittle. As a result,

the lava cracks easily.

17

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

WindsWind causes erosion by blowing away the

top layers of soil. The wind deposits this

material in other areas, changing some of

Earth’s features.

Sometimes particles of sand and dust in

the wind rub against the surface of rocks.

Over long periods of time, the particles wear

away parts of the rock.

The rocks change into

amazing new shapes.

Strong winds move sand

across beaches and create

huge hills. These hills are

called dunes. Small plants

grow in the dunes. The

plants’ roots hold the sand

in place. Sometimes high

waves drag some of the

sand back onto the beach.

Dunes act as a barrier between the ocean and the

land. They keep the land behind them from eroding.

Wind erosion

created Delicate

Arch and other

arches in Arches

National Park, Utah.

16

VolcanoesHot molten, or semi-liquid, rocks and gases

build up underground over a long period.

Then suddenly they erupt, or break through

Earth’s crust. The opening where the eruption

takes place is called a volcano. The molten

rock, called lava, flows out of the volcano.

Lava destroys things in its path. Eventually

the lava cools off and hardens. It sometimes

forms a mountain around the volcano. Or the

lava flows outward and forms new land.

Mount St. Helens Mount St. Helens is an active volcano. On

May 18, 1980, it erupted for nine hours. The

eruption blew off one side of the mountain.

The blast blew down whole forests. Ash and

rock buried other forests. Hot ash and gases

melted some of the snow on the mountain.

The melted snow caused mudflows.

Mount St. Helens before 1980

Mount St. Helens erupting in 1980

Mount St. Helens in 2006

5

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

GlaciersA glacier is a large body of ice. It forms

when snow and ice build up from year to

year. Some glaciers are thousands of years

old. One kind of glacier forms in mountain

valleys. The huge ice sheets that cover

Antarctica and the North Pole are also

glaciers.

Glaciers move downward as they grow.

They often carry parts of mountains, loose

rock, and other materials with them. This

movement of materials is called erosion.

Melting glaciers leave behind piles of rock.

They also leave large holes in the ground.

The holes fill with melted ice and form lakes.

The land surface in Antarctica is covered by an

ice sheet. Parts of the sheet are 2.6 miles (4,200

meters) thick. The ice sheet formed over 40 million

years ago.

6

Hurricanes and TornadoesA hurricane is a warm-water storm. It has

strong winds, heavy rain, and thunderstorms.

Hurricane season lasts from June through

November. The winds destroy plants and alter

the shape of beaches. Rain may cause floods.

A tornado is a spinning, funnel-shaped

column of wind. It travels across the surface

of the land or sea. Tornadoes damage or

destroy buildings and plants. Most places

have two tornado seasons. One is from June

to September. The other is from February

to April. The worst tornadoes usually occur

between February and April.

Tornadoes occur during some thunderstorms.

15

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

The effects of weather change Earth’s

surface. Heavy rains and melting snow cause

flooding. Winds blow sand and dirt around.

Dry weather may cause large cracks in the

ground. Dry weather also loosens the soil.

Wind can blow away the loose soil.

Hurricanes in 2004 The year 2004 was the worst on record for

hurricanes. There were six big hurricanes. All

of the storms caused flooding. Plants and

buildings suffered a lot of damage.

Hurricane Ivan destroyed many homes.

14

Landslides A landslide is the flow of rocks or soil

down a slope. Hills and mountains are two

kinds of slopes. A landslide usually occurs in

a kind of partnership. First, there’s a volcano,

earthquake, wildfire, or flood. This event

weakens the slope. Then gravity makes the

rock and soil move downward. Erosion from

the landslide changes the surface of the

slope. The landslide may also damage other

things in its path.

Cities and suburbs are often built too close

to slopes. Landslides may damage them.

Buildings on hillsides may weaken the land.

Then an earthquake, heavy rain, or snow

could start a landslide.

Landslides occur all over the world. They can

happen on any slope. A landslide usually starts

slowly but quickly gains speed and size.

7

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

DepositionDeposition takes place when material is

added to a landform. Wind, water, and ice

can all cause deposition.

The Florida Keys were formed by

deposition. Long ago, forests of tiny creatures

called coral grew in the ocean off the coast

of Florida. The coral built up to form a large

underwater reef, or ridge. Over time, the level

of water in the ocean dropped. The coral

died. Sand and other things built up on the

reef. The water level rose and fell a few more

times. Finally, parts of the reef were again

above water. The Florida Keys are the tops of

the reef.

There are about 800 islands in the Florida Keys.

The Keys are just over 100 miles long. Most of the

land is only a few feet above sea level.

8

C H A P T E R 3

Changes Due to Weather Weather occurs close to the surface of

Earth. Weather includes temperature, air

pressure, and humidity. Wind, clouds, and

sunshine are weather, too. Precipitation is part

of weather. Thunderstorms, lightning, and dust

storms are also weather.

Every place on Earth has weather. Some

places, like western Australia, have the same

weather for months. In other places the

weather may change quickly. One day can be

sunny and hot. The next day might be cloudy

and cool.

People enjoy sunny, warm days.

13

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

Rivers A river is a body of water that flows from

one place to another. Gravity makes rivers

flow downward. They go from a high place

into a lake, another river, or the ocean. Rivers

erode the land upstream. The current carries

mud and other material downstream. Then

deposition forms new features along the path

of the river.

A river current carries material downstream.

The current slows down at the mouth of

the river. This is where the river flows into

another body of water. The river deposits

material at its mouth. The land that is formed

in the mouth of the river is called a delta. It’s

shaped like a triangle.

The Apalachicola River Delta is in Florida. It forms

in the Gulf of Mexico.

12

Evaporation

Condensation

Runoff

Precipitation

C H A P T E R 2

Changes Due to WaterThree-quarters of Earth’s surface is covered

with water. Water makes many changes to the

land. The water cycle replaces Earth’s water.

The water cycle

is the movement

of water above,

on, and below the

surface of Earth.

Temperature, air

pressure, and

landforms all

affect the water

cycle. Most of the

water on Earth is

in the ocean. Heat

from the sun warms the water. Some water

evaporates, or changes into a gas called water

vapor. The water vapor rises into the colder

air where it changes back into a liquid. Drops

of water join together and form clouds. Some

clouds get too full of water. The water falls

to Earth as precipitation. Rain, snow, sleet,

and hail are all forms of precipitation. Most

precipitation falls into the ocean.

The same water is recycled

all the time. Drops of water

in the cycle may be millions

of years old.

9

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill

Waves A wave is the rise and fall of the water’s

surface. When waves move into shallow water,

they get taller. Their speed slows down until

they break on the shore. The waves bring

sand from the deeper ocean onto the shore.

They deposit some of the sand on the beach.

Then they wash over it and take away small

particles. Currents near the shore carry sand

along the ocean floor near the beach. The

currents deposit the sand. It builds up and

forms sandbars. Strong waves also break up

rocks on the beach. Over time, the rocks

wear down and become small bits. The

shoreline is always changing because of the

constant motion of ocean waves.

Protecting beaches is very important. Workers

add new sand to the beaches. City and state laws

protect beaches from too much use.

10

TsunamisA tsunami is a series of huge waves.

The wind does not cause a tsunami. An

underground earthquake or a volcanic

eruption causes a tsunami. Most tsunamis

occur in the Pacific Ocean. As the tsunami

travels through the ocean, it gains strength

and speed. The tsunami pushes huge

amounts of water onto the shore. The force

of the water changes the shape of the

beach. It destroys things in its path. The

water floods the land.

A tsunami formed in the Indian Ocean in

2004. Indonesia and 10 other countries had

floods and other damage. This was the worst

tsunami in history.

11

Ch

an

gin

g E

art

h©

Ma

cm

illa

n/M

cG

raw

-Hill