Let's Do Science 3 – Text Book B

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P mary 3 Prr i ma 2 Textbook

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The 5E Model – Guided Inquiry

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The Let’s Do Science series is based on the Biological Sciences Curriculu Curriculum riculu Study (BSCS) 5E teaching and learning instructional model. The he 5E E model is centered on the idea that students understand science concepts oncepts pts best by using prior knowledge to pose questions and find answers rs through hrough guided inquiry.

This hands-on approach, integrated with engineering ng g and design skills, sk s has students learn science by doing science. Teachers chers guide the llearning process and are able to assess student performance evaluating student mance ce by evalua explanations and the application of newly acquired quired d knowledge knowledg knowled and skills.

Engage

The Engage phase of the 5E model provides videss students with w the opportunity to demonstrate their prior knowledge and understanding of the topic or understand concept. Students are presented with which serves to h an n activity or question q motivate and engage students as they hey begin the llesson. Teachers identify and correct any misconceptions and d gather data dat from students which will guide informed teaching and learning. earning. ng Essential to stimulating and students is the use of mixed media d engaging gaging stude st such as colorful photos, illustrations found throughout the trations tions and diagrams d textbooks and activity books.

Let’s Science also includes extensive bo boo t’s Do S digital resources such narrated videos, interactive lessons, virtual labs, h as narra nar id slideshows and more. re.

Explore

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This phase encourages exploration of concepts and skills through gh handshan on activities and investigations. Students are encouraged to work togethe together red learning earn and apply various process skills while gaining concrete, shared ch students experiences. These experiences provide a foundation for which epts.. This studentstuden can refer to while building their knowledge of new concepts. centered phase comes before formal explanations and d definitions of tthe concept are presented by the teacher.

Explain

This phase follows the exploration phase and iss more ore teacher-directed. teacherteache Students are initially encouraged to draw on their learning experiences and earning ex e oncept ept through explanations e demonstrate their understanding of the concept and he opportunity pportunity to t demonstrate discussion. After the students have had the their understanding of the concept, the formal e teacher cher then introduces in definitions and scientific explanations. also clarifies any s. The teacher eache al erged during the th Explore phase. misconceptions that may have emerged

Elaborate

In the Elaborate phase, students nts refine ne and consolidate co c their acquired knowledge and skills. Opportunities for students to further rtunities nities are provided pro apply their knowledge and skillss to new situations in order to broaden si and deepen their understanding rst ng g of the concept. Students may conduct additional investigations, share information and ideas, or apply their ns, sh shar orm knowledge and skillss to other ther disciplines. d disc

Evaluate

This final phase se includes cludes both formal form and informal assessments. These can include concept models, journals as well as more traditional cept maps, physical phys ummative ative assessm assess forms of summative assessment such as quizzes or writing assessments. e encouraged to review and reflect on their own learning, and Studentss are on theirr newly wly acquired knowledge, kn understanding and skills.

Let’s Do Science Let’s Do Science is based on the United States Next Generation Science Standards (NGSS). The series consists of full-color textbooks and full-color activity books for Grades K to 6.

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Charact

Fish are anim live in the oc can also be such as stre

Let’s Do Science engages students with a highly visual al presentation of the disciplinary core ideas in the textbooks xtbooks books and places an emphasis on applying scientific knowledge nowledge ledge using NGSS practices through numerous scientific tific investigations. Let’s Do Science sees engineering ring ass an essential element of science education and tightly d as such is tight integrated into both the textbooks and activity ctivity books.

Most fish re some give b

The Let’s Do Science textbooks include e the following ffeatures:

Think Deeply

d In the Field

Topic-related questions for group discussion aimed at deepening students’ understanding of the topic.

62

Ecologistt

n and ms an isms rrts of organisms orts or alll so al in all d in ed ted erested eres ter te nterested nteres e iinteres ou are you If yo he hen ent,, tthe environment envir heir environment he th the n their hin hin th ithin within ct with c act ract erac eract nteract in y int ow they how h o ologist. ologist. ecol eco be an e o be ke tto ke you’d like yb yo aybe maybe

on ons eractions eracti nteracti nt int their in nd their and ngss a ng ings things g th ing l ing lilivi off liv ty o munity mmunity A comm tem. tem tem. ystem ys sys o osys cosys c co ec ca ed an e call ent is called ment nm onm rron iron nviro nviron environ ir e h their th with with wi ese hes th ess these ies die tud who stud st w ientist cient scie sci scientist is a sscient st is ec gist eco n ecologist An s.. ms. ems. em e tems. c cosystems ecosys eco ec e ecos and ons a ractions erac e interacti of interacti ange o range ra e ran dy a wide ud ttudy stss stu iists gist log olog colog Ec Ecolog ma m ey may em. The o stem co cosyst ven ec v given n a given hin with sh s wit nship nshi nsh onshi tionship atition rela re relati all small a sm such as m such tem y tem osys cosy eco an ec arts of an mall parts small smal sma y sm study e ge ag d lar udy a so stu y al ey may The Th oil. The so e soil. tthe g in th iving iv liv ugss lliving ugs bu bugs n an ocea the ocean ns in the ation a lation p p la h popu a fisssh ch as uc u uch su ctionss such e actions teractions ntera intera her here. atmosphere. th atmosp ct the ffec efffec eff rests ef ores or o orests nffforests nforests rainf ho rainf or how or

Engineer It!

Goes beyond inquiry uiry by encouraging students udents to design, model and build utions to to engineer solutions oblems. defined problems.

A Closer Look Graphing Weather

Scientists are e con onstant onstan antly ntltly co collec e ng data about the ecting ectin weat w Th They he ather ather. ey o ofte ften create create tables tables and grap aphs to em un underrsstand sea onal sseaso nal chang ta cha es in weather. Tables help them ables an and charts are also a way to t comm useful us ommu unicate we weather inf i forma matio tion n to pe people.

133 Let’s t’ take ake a look at the yearl ye y chang ges es in weath weat er for Franci ancisc San sco, o, U United nited States.

132

Average Daylight Hours – San Francisco Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 10 11 12 13 14 14.5 14.5 13.5 12.5 11.5 10 9.5

120 mm

Average Precipitation

– San Francisco

100 mm 80 mm

In the Field

Inspirational sc sciencerelated to ated professions p stir interest rest in sciencerelated careers.

A Closer Look

Invokes enthusiasm in science by presenting interesting topics beyond the syllabus.

60 mm

40 mm

20 mm 0 mm

Jan

68

Feb Mar Apr May Jun

Jul

Aug Sep

Oct Nov Dec

Amazing Fact!

Interesting facts to bui build interest and enthusiasm. nthusiasm.

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fish gills

stingray

eat white shark

Fish have body parts well-adapted to life in water. They have gills to take in oxygen from the water. They have fins and tails to help them swim.

teristics of Fish

mals that live in water. Most fish cean, which is salt water. Fish found in freshwater habitats, eams, rivers and lakes.

Extra ra information to t build students’ dents’ knowledge know se of the cu base current topic.

‘fish’ in its name. Do you think a starfish is a fish?

Explain your answer.

Like reptiles and amphibians, fish are cold-blooded.

eproduce by laying eggs, but birth to live young.

Did You Kno Know?

Think Deeply

Try This!

Optional ptio hands-on activities to be conducted activ in groups or at home.

63

Science Words

Use the words to comp lete the sentences. mammals metamorphosis fish insects pupa 1.

Review

1.

oxygen invertebrates amphibians larva chrysalis

Animals need a specia l part

vertebrates birds reptiles caterpillar

of air called

Animals with a backb one are Animals without a backb one

4.

are animals with a body covered in fur.

They give birth to live young.

5.

6.

7.

8.

9.

.

are called

are the only animals with

are cold-blooded with

A change in body form

.

a body covered in feathe rs.

a body covered in scales

Frogs and salamander s are

or plates.

. They have smooth, moist

during g an animal’s l s life cycle

live in water and have

2.

List three vertebrate anima als. l

3.

List three invertebrate

4.

How are mammals differe d nt from m most other animals reproduction? in terms of o

.

2.

3.

called

List the needs of anima ls.

is called ll d

gills to help them take

an animals.

5.

List the characteristics so of birds.

6.

List four kinds of reptile s.

7.

How is the life cycle of

8.

List the he characteristics h

9.

Descri escrib be e insect insec s in term terms of their

birds similar to that hat of

10. Classify the he animals as either

skin.

(a)

reptiles?

of fish.

number of legs and body parts. .

(b)

.

in oxygen.

Discussion

(d)

15oC 10oC 5oC 0oC

AB

How does the weather change throughoutt tthe year in San Franci cisco? s

77

Avera ve ge M Maximum Temperatt ure – San Franc Fr isco o

25oC 20oC

Jan

Feb Mar Apr p May Ma Jun

J Jul

Aug Sep p

Review

Oct Nov Dec

Activities 9.7 – 9.8

69

Links students to the Let’s Do Science Activity Book at the appropriate juncture.

verteb v rates or invertebrates

(c)

76

AB Activity

Topical questions at the end of each chapter for formative assessment.

Topic-related questions and situations for class discussion to build a deeper understanding of topics.

Science Words

Lists the essential science vocabulary covered in each chapter.

Let’s Do Science – Contents 2

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Unit 7 – Earth and Space

Movement of the Earth The Earth’s Moon Our Own Star – The Sun Our Solar System Review

Unit 8 – Rocks and Soil

Minerals and d Rocks ocks Ro Using Minerals and Rocks ?

What Is Soil? g for f Soil Using and Caring w Review

Unit 9 – Weather Weathe and Climate te Understanding Weather Understa Measu Measuring Weather Ext Extrem Extreme Weather W Weather and Seasons Cli Climate Climate Change Review

4 8 10 12 23

22

28 38 41 44 47

50

52 53 64 66 70 76 79

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What Is Matter?

States of Matter Heating Matter Cooling Matter w Review

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Unit 10 – States of Matter

Unit 11 – Interactionss and Fo Forces Position ition n and and Motion What Is a Force?

F ce?

Balanced Unbalanced Forces Balance e and Unba ed Predicti n Motion Predicting Review ew

Unit 12 – Forms Form of Energy What Is Energy?

Sound Li Light al Energy Thermal Review R

84 8 86 90 92 94

96 98 106 122 126 129

132 134 136 140 144 147

Earth and Space

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In this chapter you will ...

• explain how the rotation of the Earth causes es us to experience day and night.

• explain how the revolution of the Earth around the th Sun causes parts of the Earth to experience e seasons. seasons • describe the movement of the Earth’s h’s moon. moon • describe how the Sun affects the he Earth.

• list the planets and other objects our solar system. bjects in ou What objects can be found und in space? spac How do the objects move? ve?

2

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What objects make up our solar system?

Go Online!

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Access interactive content relating to this topic on the NGScience website. ngscience.com

What is space exploration?

What data do scientists collect when they explore space?

3

Movement of the Earth

on

Rotation – Day and Night ght Why do we experience day and night on Earth? rth?

In space, the Earth moves oves in different differen ways. One way the Earth arth moves is by spinning on its axis. An axis is an imaginary line that runs through throug the Earth’s center. This spinning movement on m its axis is called a rotation rotation.

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As it rotates, s, part art of the Earth is facing the Sun. This his part of the t Earth is lit up and experiences daytime. At the same time, eriences daytim the opposite side of the Earth is facing away ay from the Sun. This part of the Earth is in darkness and it is night-time.

4

It takes the Earth 24 hours to complete one rotation. The repeating rotation of the Earth is why we experience the daily pattern of day and night.

The part of the Earth facing the Sun is in daytime. The part of the Earth facing away from the Sun is in night-time.

Amazing Fact!

The planets in the solar system rotate about their axis at different speeds.

This means the length of a day on each planet is different. One day on Jupiter takes just 10 Earth hours. One day on Venus takes 243 Earth days!

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Go Online!

In what othe other way does move in space? the Earth m

Observe how the Earth rotates on its axis and the daily pattern of day and night on the NGScience website.

QuickCode: B7M9

AB

Activity 7.1

5

Earth’s Orbit and Seasons Amazing Fact!

As the planets are different distances from the Sun, they take different times to complete an orbit. This means the length of a year is different on different planets.

Mercury is the closest planet to the Sun. One year on Mercury is just 88 Earth days.

On the furthest planet from the Sun, Neptune, one year is 165 Earth years!

As the Earth rotates about its axis, it also o revolves in a curved path, called an orbit, rbit around the Sun. One complete orbit of the Sun is called a revolution. It takes the Earth 365 days to complete a revolution, olution, which is i one Earth year.

The Earth can be divided into parts to two part called hemispheres. The upper part of the Earth is called the Northern hern Hemisphere.

Hem The lower part of the the e Earth is called ca Southern Hemisphere. here Recall that the Earth arth rotates about its axis.

The axis is not ot straight up u and down. It is tilted at an angle. This means that as the Earth orbits one hemisphere is its the Sun, o tilted towards Sun and one wards the S hemisphere phere is tilted tilte away from the Sun.

Go Online!

June

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Observe the movement of the Earth around the Sun on the NGScience website.

QuickCode: K8J9

The hemisphere tilted towards the Sun gets more direct sunlight than the hemisphere tilted away from the Sun. This causes changes in weather patterns in different parts of the Earth at different times of the year. These changing weather patterns are called seasons.

6

When the Southern Hemisphere is tilted towards the Sun it is in Summer, while the Northern Hemisphere is in winter.

Think Deeply In December, er, many countries in n the Northern Northe Hemisphere e are in i winter.

What month would countries tries in the Southern Hemisphere be in winter?

tio n

When the Northern Hemisphere is tilted towards the Sun, it gets more direct sunlight and is in summer. The Southern Hemisphere is tilted away from the Sun and gets less direct sunlight. It experiences winter.

March

December

September

How does the weather change from season to season in your area?

7

The Earth’s Moon oon

Amazing Fact!

Many scientists believe the moon formed when a small planet crashed into the Earth.

Rock and dust were thrown into space. Gravity pulled the rock and dust together to form the moon.

In space, the force of gravity ravity causes caus smaller objects to orbit objects. Any rbit larger o nother ob object that orbits another object is called sa a satellite. The Earth is a satellite of the Sun. The Earth’s moon orbits orb the Earth, so the moon n is a satellite of o the Earth. It takes n about 27.3 days d the moon to revolve once he Earth. around the It also moon about 27 days to o takes the m te once on o its axis. So, the side of the rotate on facing the Earth is always the same. moon On some nights, the moon appears in the sky as a bright circle. The moon appears bright because it reflects the light from the he Sun. On other nights, the shape of the moon is different. The changing shape of m the moon’s sunlit portion, as viewed from Earth, is called the phases of the moon.

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8

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As the moon orbits the Earth, part of the moon is lit up by the Sun while the other part is in darkness. The moon appears to change shape because the part of the moon lit up by the Sun changes as the moon orbits the Earth.

When the whole side of the moon seen from Earth is lit up, we see a full, round moon. When hen only half of the side of the moon seen from o Earth is lit up, we see the moon in the he shape of a semi-circle.

AB

al e

What causes the phases of the moon?

Activities 7.2 – 7.3

Think Deeply

Why are we able to predict the shape the moon will appear in the sky?

Go Online!

Learn the names of the different phases of the moon in a video on the NGScience website.

QuickCode: H3C1

9

Our Own Starr – The Th Sun Amazing Fact!

During ng the day, day the brightest object in the sky is the Sun. The Sun is a star. It is the closest losest sstar to the Earth.

The S Sun lights up the Earth during the day and an keeps us warm. Without the light ight and heat from the Sun, there would be no life on Earth.

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If you could fly on a commercial plane from the Earth to the moon, it would take more than two weeks. To travel by plane from the Earth to the Sun would take about 20 years!

If you look into the night sky on a clear night, you are likely to see many bright m ghts spots a spots. These brights are stars. A lar e, hot ball of glowing star is a very large, gases. Allll stars are ver very large. They appear ass small dots in the night sky because they are so s far from Earth.

Think Deeply eply

How would the Earth be affected if it were e closer to the Sun? How would it be affected iff it were further away?

10

Although the Sun is the closest star A tto Earth, it is still very far away. The distance between the Earth and the moon is about 384,400 kilometers. The distance between the Earth and the Sun is about 150 million kilometers.

AB Activity 7.4

11

Our Solar System Planets A planet is a large ball of rock k or gas that th revolves around a central star. The Earth, Ea the planet we live on,, is the only known kn planet to contain life. star that e. The central st the Earth orbits is the are he Sun. In all, there t eight planets orbiting g the Sun.

Venus Mercury

ars Mars Earth

Jupiter

These planets, their moons and T other objects orbiting the Sun make up our solar system. In order of their distance from the Sun, the four closest planets are Mercury, Venus, Earth and Mars. These planets are called the inner planets. They are made up mostly of rock. Due to their close distance to the Sun, the inner planets are also much warmer than the planets further from the Sun.

12

Amazing Fact!

Although AlthoughMercury Mercury ercuryisisthe the closest planet closest planet Sun, anettotothe theSun, Su Venus Venusisisthe the hottestplanet planet ehottest pl ininour solar system!

This our solar system! Thisisis because because ofthe themake makeup up useof of its thick atmosphere. of its thick atmosphere. atmo During Duringthe theday, day, the daythe temperature on its temperature surface temperatu on itssurface can reach more than can reach more than440 440 degrees degreesCelsius!

Celsius!

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The outer planets are the four furthest planets from the Sun – Jupiter, Saturn, Uranus and Neptune. These planets are much larger than the inner planets. They are not rocky like the inner planets. Instead, they are made up mostly of gases. They are often referred to gas giants.

Uranus Uran

Neptune Saturn

Did You Know?

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Besides Mercury and Venus, Ven all of the planets p in the solar system have e one or more moons.

Our planet, Earth, has just moon. Mars has ust one m two moons. The planet moons et with the most m is Jupiter. It has 79 moons. largest moon, oons. Its la Ganymede, is larger ger than the planet Mercury!

Earth h is the only planet pla in e solar system k the known to contain life. Why is this so?

Scientists once considered there to be nine planets in the solar system. This included a small icy planet beyond Neptune, called Pluto.

In 2006, scientists decided that Pluto was too small to be considered a planet and classified it as a dwarf planet.

AB Activity 7.5

13

asteroids

ed

Other Objects in the Solar System Besid the Sun, planets and their Besides moons, what other objects can be moo found in the solar system? foun

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There are many different objects in the solar ssystem. Some, such as space rocks, Others objects, such as are natural. n communication satellites, have been sent co into space by people.

Did You Know? ow?

Beyond Neptune is a large arge belt of ice rocks called the Kuiper belt. The belt is around 2,000 ,000 times larger than the e the asteroid belt and iss also home to th the dwarf rf planet Pluto.

14

One O of the most commonly found objects in space are asteroids. Asteroids are large rocks that can range in size from just a few centimeters up to thousands of kilometers.

Most asteroids orbit the Sun in an asteroid belt between the planets Mars and Jupiter.

du ca tio

comet

Like asteroids, comets are made up of large chunks of rock. However, comets are also composed of ice, water and dust. Comets are often seen with a long tail which is mostly due to the dust that is left behind by the comet. The size of most comets ranges from around 700 meters to 20 kilometers.

Asteroids and comets often break up into smaller pieces and form meteoroids. Meteoroids have a size e ranging from a grain of sand to one meter.

If a meteoroid enters Earth’s atmosphere, it becomes known as es kn a meteor. Most meteors burn u up completely before reaching Earth’s aching the E surface. Have you ever er seen a shooting s star? It was most likely meteor kely a mete burning up in the e Earth’s atmosphere. atm Occasionally, doesn’t burn up y, a meteor doe completely as it enters the atmosphere.

A meteor teor that reaches reach the Earth’s surface face is called a meteorite.

meteor

Amazing Fact!

About two billion years ago, a giant meteorite hit the surface of the Earth. It created the largest crater on Earth – the Vredefort Crater. It is more than 300 kilometers wide!

15

Did You Know?

The Soviet Union launched Sputnik 1, the first man-made satellite, into space on October 4, 1957. Sputnik 1 completed a full orbit of the Earth every 98 minutes. After three months of orbiting ng the Earth, Sputnik 1 burned urned up on re-entry into the Earth’s atmosphere. sphere.

Some satellites in the solar system are manmade and have been launched into space by people. They are used for communication, cation, weather forecasting and can provide us with accurate information about locations ns on Earth.

Ear Some satellites are used to observe and gather g data about other objects in n the solar system, syste such as planets, moons and nd the Sun. Space telescopes are man-made satellites in s space. They are used to things further away o see thing and more clearly than an telescopes telescop on Earth.

d

Sputnik 1

co communication satellite

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Hubble Space Telescope

Amazing F Fact!

One of the largest is the Hubble Space Telescope. pe.

It has been observing objects in the solar system em and beyond since 1990. It has helped scientists learn many things about space.

Shortly after its llaunch in 1990, scientists noticed that the cientists notic Hubble Space Spa Telescope had focusing on distant trouble fo objects. Astronauts were sent space to fit a new set of into sp focal mirrors to the telescope. foca Much Mu like putting on a pair of glasses.

People often go on missions aboard space crafts launched into space by powerful rockets. ckets. The Th International Space Station (ISS) is the he largest man-made object in space. The ISS is a giant space laboratory that orbits the Earth th with up to nine astronauts on board. The astronauts carry stronauts ca out experiments about living in space in a hope to one day make living in space e or even on other planets possible.

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AB Activity 7.6

Powerful rockets are used d to launch man-made made objects objectss and people into space. spa

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Go Online!

People have long been fascinate fascinated with space.

The searching, observing collecting of data ervin and c pace exp in space is called space exploration. Through on, people a space exploration, are able to learn more about the object objects in space, their properties and the patterns in whic which they move. Space exploration done using observation and on can be do monitoring on Earth. It can also be ng instruments instrum done by sending o objects or people into space.

To observe o objects in space from Earth, scientists use powerfu powerful telescopes. A telescope is an instrument that makes objects that are far away look loo closer and clearer. This allows scientists to observe in greater detail. obser bserve e distan distant objects o

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On July 20, 1969, pilot Buzz Aldrin landed the lunar module ‘Eagle’ on the surface of the Earth’s moon.

On July 21 at 2:56 a.m.

Commander Neil Armstrong stepped off the ‘Eagle’, becoming the first human to walk on the surface of the moon. Watch this amazing and historic event on the NGScience website.

QuickCode: T4P3

Space Exploration ation

The Gran Telescopio Canarias is one of the largest telescopes on Earth. It has been exploring space since 2009.

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Amazing Fact!

The Nationall Aerona Aeronautics and Space e Administration Administrat (NASA) have e sent five space robots, s, called rovers, rover to the planet et Mars. They Th collect data about the planet’s surface send the data urface and se back to Earth Ear for analysis.

The latest rover to land on Mars, called Perseverance, ca left Earth on July 30, 2020 Ea and nd touched down on February 18, 2021. On board Feb the rover is a small robotic helicopter called Ingenuity.

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Another way that scientists explore space is by sending objects into space to make observations and collect data. These objects, called space probes, include space telescopes, robots and satellites.

Space probes collect data about space objects and conditions.

They may also collect and analyze samples of objects or take photographs and videos. The data collected by space probes is sentt back to Earth where scientists study and interpret the data.

People also explore space pace by venturing into space in n space crafts. Scientists that travel ravel into space, called astronauts, onauts, are highly trained in operating space crafts and living in n space. In space, astronauts uts collect data and a do experiments nts that th cannot be done on Earth.

R

Large e rockets ar are needed to get ects and peop objects people into space.

Engineer It! Design and build your own model of an exploration robot to explore the surface of Mars. What data will it collect?

What features will it have to collect the data?

What types of experiments might astronauts carry out in space?

19

A Closer Look

The International Space Station There are about eight billion people living on Earth. That’s a lot of people! people Did you know that at this moment, there are a small group of people eople that don’t d live on Earth – they live in space aboard the International nal Space Station.

Statio The International Space Station (ISS), is a large satellite e that orbits the Earth.

It’s the biggest man-made object in space and travels at a speed of about 27,000 kilometers per hour. In just one day, it orbits the Earth 16 times.

Since the year 2000, up to nine astronauts and cosmonauts cosmonaut have been on board the ISS at any one time. They are highly-trained -trained to live and work in space.

Go Online!

a

Learn more about the International Space Station in a video on the NGScience website.

QuickCode: P4S6

International Space Station (ISS)

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You can think of the ISS as a giant science laboratory in space. Each day, the people on board carry out investigations about living in space for long periods of time. The data h collected on board the ISS is sent back to Earth and shared with many different countries.

d

In what ways is living in space ce different from living on Earth??

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Science Words

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Use the words to complete the sentences. axis rotation orbit Northern Hemisphere Southern Hemisphere seasons solar system

revolution planet satellite phases of the moon asteroids comets meteoroids

star meteor or meteorite meteor space exploration explor telescope space probes pro

1.

A

2.

The Earth spins on its every 24 hours.

3.

Any object that orbits another object bject is called a

4.

on’s directly direc sunlit portion, as viewed The changing shape of the moon’s . from Earth, is called the

5.

The Earth is divided into two The upper part of the Earth is called wo parts. T the . The he lower l partt is i called the .

6.

is a very large, hot ball of glowing owing gases. gases . It completes ompletes one on

.

are chunks hunks of rock, ro ice, water and dust.

7.

Asteroids and comets oft often break up into smaller pieces and form .

8.

The Earth curved path, called an h moves in a c Sun. It takes the Earth 3 365 days to complete one

9.

The revolution of the Earth around the Sun causes changes in weather patterns cal . called

10. A central tral star.

22

, around the of the Sun.

is a large ball of rock or gas that revolves around a

11.

A meteor that reaches the Earth’s surface is called a

.

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12.

is the search, observation and collection of data in space.

13.

A is an instrument that makes objects that are re far away awa look closer and clearer.

14.

All of the planets, their moons and other objects orbiting the Sun make up our .

15.

are large rocks that can range in size from just jus a few centimeters up to thousands of kilometers.

16.

A meteoroid that enters the Earth’s atmosphere sphere is called a

17.

are objects sent into space e to make observations and collect data which is sent back to Earth for analysis. ana

.

Review

1.

What causes the alternation on of day an and night on Earth?

2.

What causes the changes in seaso seasons on Earth?

3.

How long does it take e for: (a) the Earth to complete one o rotation? (b) the Earth to complete one revolution of the Sun? n to comple (c) the moon complete one revolution of the Earth?

4.

List the planets system. Indicate which are the inner planets nets in the solar s and which outer planets. ch are the oute

5.

Why are the ou outer planets much colder than the inner planets?

6.

Listt three typ types of satellites sent into space by people.

7.

What are space probes? What do they do?

23

National Stadium, China

Guggenheim Museum, Spain

Space Architect An architect is a person that designs structures such as skyscrapers, sports arenas, museums and houses. The purpose of their designs is to serve a function and have a form that is visually appealing.

The Guggenheim Museum in Spain and the National Stadium um m in n China are examples of spectacular ctacu culla ar architectural designs.

One very unique type e of of architect ar ctt that requires a lot off scientific scientifiic c knowledge and research esear arch is is a space space sp architect. A space architect ce ea rch rchitec hitect designs designs space crafts an and structures nd structur sttru uctu ure es ffor or humans to live ive in no outer ute er spa sspace! pace!

The environment ironment ment in space is not a friendly y place ace for people to t live. There is no can change o air, ai , temperatures temperatu c from om m freezing to boiling b boilin very quickly and an nd there ere iss no no gravity. grav

24

a ti

In the Field

These factors facto must be considered space architects design when spa and living quarters. sspace pac crafts c They ey must have very good knowledge about materials and k now ttheir h properties. They have to consider if materials will be safe and suitable for the fast changing environment in space. It’s not easy getting things into space, so the materials they choose also have to be lightweight and very strong.

Space architects focus mainly on how their structures will function and not so much on how they look. There aren’t many people around to admire the outside of a space station!

25

Rocks and Soil

le du ca tio n

8

In this chapter you will ...

• describe minerals and rocks and where they can be found on Earth.

sh between • describe how rocks are classified and distinguish the three main types of rocks.

• describe soil and how it is formed.

• list the layers of soil.

scribe the importance imp • list ways people use soil and describe of caring for soil.

What are rocks and minerals? nerals?

How are they used by people? eople?

26

ga le du ca tio n Go Online! ne!

What makes up soil?

Where does soil come from?

Access ss interactive interacti content relating to this ttopic on the website.

NGScience we ngscience. ngscience.com

27

Minerals and Rocks Amazing Fact!

Diamond is a mineral.

It is the hardest natural substance on Earth. The only other thing that can scratch a diamond is another diamond!

du ca tio n

What Are Minerals?

Minerals are non-living substances ces that hat are ar formed naturally in the Earth. They y are usuall usually found underground, in rocks and soil. Minerals Minera Mine are also found underwaterr in rivers, lakes a and the ocean.

Minerals are made off chemicals. hemicals. They The do not come from the remains mainss of living things. tth You are already many types of y familiar miliar with m minerals. Metals, als, such uch as gold, go gold silver, iron and copper are minerals. erals. Quartz, Quart salt and talc are minerals too. oo.

quartz quar

R

Himalayan ro Himala rrock salt

28

gold

What Are Rocks?

Rocks can be found all over the Earth’s surface. They can be found on mountains and hills, in fields and valleys and along rivers and streams. Rocks line our coastlines and can be found underwater too.

AB

Activity 8.1

d

In what ways are rocks similar to each other?

How can rocks be different?

ca

Rocks are naturally occurring non-living things found on and under the Earth’s surface. All rocks are made up of one or more minerals.

Amazing Fact!

The largest single rock formation in the world is Uluru in central Australia.

The gigantic rock reaches a height of over 850 meters above ground and another 2.5 kilometers below ground!

29

Properties of Rocks

al ed uc ati on

Rocks are made up of tiny mineral particles ticles called grains. Rocks can have different erent nt properties propertie such as color, texture and arrangement gement ent of the t grains that form them.

These rocks are different in n color. co color

Try This!

In small groups, go into your schoolyard and collect small rocks. Discuss the properties of the rocks.

Classify the rocks in two different ways.

rough rockss

30

These in texture. e rocks cks are different diffe

smooth pebbles

ed uc ati on

These rocks have grains of different sizes.

Re ga

The grains in these rocks are arranged ed in n different ways.

What at are some properties pro of your schoolyard? the rocks in y

AB Activ Activity 8.2

31

How Do Rocks Form?

Go Online!

Learn about different types of rocks and how they form on the NGScience website.

QuickCode: Q5F4

tio n

Scientists who study rocks, called geologists, eologists, ogists, often classify rocks by how they form. orm.. They can be classified into three main groups oups – igneous igneo rocks, sedimentary rocks and metamorphic tamorphic rocks.

Beneath the surface of the he e Earth, temperatures tempe temp can be very hot. It can be so o hot that rock r exists in a liquid (molten) form rm, called mag gma. form, magma.

Igneous rocks form orm when magm magma mag cools and returns to a solid d state. ate.

a

Granite Gra ite forms form when whe magma cools beneath ols slowly be beneat the Earth’s surface. surfac

32

Other times, heat and pressure cause magma to break through openings in the Earth’s surface, called volcanoes. The magma flows onto the Earth’s surface as lava. The lava cools rapidly and forms solid rocks such as basalt.

Think Deeply Dee

tio n

Sometimes, magma cools slowly beneath the Earth’s surface and forms rocks such as granite.

How are magma and lava similar?? How are they different? Draw a picture or create a Venn diagram.

Basalt is an igneous rock that forms when lava cools rapidly.

33

uc ati o

sandstone

On the surface of the Earth, rth, h, weathering a and erosion break down rock of k and the remains rema rem living things into small particles. rticles. Wind and water transport these particles ticless to areas of o dry land, into rivers, lakes and Groups of these nd the e ocean. G particles settle to o form rm sediments. sedimen Over many years, form and rs, layers of sediments s are pressed forming new rock called ed together ether form sedimentary rock. ntary rock roc t k.

Common rock include mon n types of sedimentary se sandstone limestone. ndstone ne and lim In sedimentary edimenta rock, it is often possible to see the layers sediment from which they are formed. yers rs of sed layers of sedimentary rock s

34

limestone

ca tio n

Metamorphic rocks are formed when igneous and sedimentary rocks are subject to heat and pressure beneath the Earth’s surface. Over time, the heat and pressure cause the rock to change form. The new metamorphic rock that forms has different properties from the original rock.

Heat and pressure beneath the Earth’s surface can cause limestone, a sedimentary rock, to change to marble, a metamorphic rock.

Think hink Deeply Dee

How iss the formation form metamorphic rocks of metamorphi similar to the formation of rocks? igneous roc

Slate is another type of metamorphic rock. It is formed from the sedimentary rock, shale.

eg al

Slate is a metamorphic morphic phic hic rock formed from m shale. ale

Pink and d gray layers of the metamorphic amorphic rock, gneiss. gne

Marble is a metamorphic rock formed from limestone.

35

A Closer Look

The Rock Cycle

ga le du ca t

Over millions of years, the weathering of rocks and soil on the Earth’s surface along with heat and pressure beneath the Earth’s surface cause rocks to continually change from one form to another. This process is called the rock cycle. igneous rock

36

Trace the rock cycle diagram. With a classmate, discuss how rocks are formed at each stage.

ed uc ati

AB Activity 8.3

ga

sedimentary rock

metamorphic rock

37

Re ga le du ca ti

Using Minerals nerals rals and Rocks Minerals and rocks ocks are very useful u us to people.

They are used ways. d in many different differ Iron is a mineral ral we use to t make the metal steel. We use construct buildings and se steel to co build bridges. Copper is a mineral used to wires mak make ke electrical e wire and water pipes.

Aluminum Alumi A nu um comes com from a mineral called bauxite. bauxxitte. We use aluminum to make a variety of objects, such as cans, tin foil and parts objec o bje of o cars, ca boats and bicycles.

38

Minerals such as gold and silver are used for making jewelry. Gems like diamonds and rubies are minerals too.

Calcium is a mineral found in dairy foods.

It helps to keep your bones strong and healthy. Many other foods contain minerals that help to keep us healthy.

uc a

Discuss some of the ways we use minerals from day to day.

Gold, diamonds and rubies are minerals commonly used to make jewelry.

AB Activity 8.4 Did You Know?

Fluoride is a mineral found naturally in water, rocks and soil. Fluoride is often added to toothpaste to strengthen teeth and help prevent tooth decay.

39

orate our ou We use rocks to build walls and decorate homes and gardens too.

Look around your home or school. What are re some ks? ways we use rocks?

Re ga le d

The Great Pyramids of Giza were built more than 4,000 years ago as tombs for the ancient rulers of Egypt.

The pyramids are made of more than five million limestone rocks.

Like minerals, rocks are used by people in many ways. We use rocks for building houses, roads and sidewalks.

ati o

Amazing Fact!

Think Deeply Deepl

What hat properties of rocks make ake them suitable to t the ways they are used ple? by people?

40

What Is Soil?

An important part of soil is humus. Humus contains the remains of dead plants and animals and is often darker in color than other parts of soil. Humus adds nutrients to the soil which are essential to plants and other living things.

AB Activity 8.5

Think k Deeply

ca tio n

Soil is a mixture of weathered rock, minerals and other living and non-living things. In between the small pieces that make up soil are spaces that contain air and water.

When gardening, ardening, people often add extra ‘topsoil’ ‘top to gardens. How does this help plants grow? grow

Many plants need soill to survive. surviv ve. ve e Plan Plant antt roots grow down into take o the soil and a ta e in the nutrients, minerals inerals and water wat ater the e plants need to live grow. As plants ve and gro are the main source urce of food for or people and other animals, important nimals, soil is im ortant to all life on Earth. h.

Many any animals, such suc as ants, worms and other burrowing animals also live in soil.

41

How Soil Forms

Compost is a soil very high in nutrients. It is made from the decomposition of organic matter – usually plant parts.

You can make compost by putting food scraps in a compost bin in your garden.

A compost bin is like an upside-down trash can.

The pieces of weathered rock ck are carried b by wind and water to new places. aces. ces. The remains remain remai of dead plants and animalss also form part par of the developing soil.

As more weathered d rock ck particles are added over time, soil begins ginss to form in layers. la

The soil layer closest of the Earth st to the surface ssu is called topsoil. psoil. This part of o the soil contains lots of humuss and nutrients. Topsoil also has d is rich in n nu large spaces paces aces for air an and water. Most plants and soil-living soilving animals get the things they need from the th he topsoil. to oil. il

Re ga l

compost p

du ca tio n

Did You Know?

Soil forms when wind, water and changes hanges ges in temperature break down rocks into to small mall pieces. pieces This process is called weathering. ng.

42

Soil forms in layers.

ati on

Below the topsoil is subsoil. Subsoil contains less nutrients and smaller spaces for air and water.

Below the subsoil is a layer of weathered rock fragments that sit on a layer of bedrock.

top topsoil (organic layer) psoil ((o

subsoil

weathered rock particles

bedrock

R

Try This!

AB A Activity 8.6

Use a clear plastic cup and art and craft materials to build a model to show how soil forms in layers.

43

at

Using and Caring aring for Soil How People Use Soil Soi Soil is used by people in many m ways. e soil to o grow gr Farmers use the plant crops that we d. They also als use soil to raise the animals eat for food. ovide us with wit milk, eggs and meat. People that provide also use soilil in gardens to grow vegetables and se soi ng fruits, or plants for decoration.

g

Pla ants that grow in soil are also used by people to Plants make fabric, such as cotton, which is used to make fa clothes Trees also need soil to grow. Trees provide clothes. peop with the wood we need to build houses or people bur for fuel. burn

44

AB Activity 8.7

uc ati on

Caring for Soil

Soil takes a long time to form. Just one centimeter of soil can take up to 1,000 years to form. Because it takes so long to form, it is important that we care for soil.

We can care for soil by preventing erosion.

Erosion can occur when we remove e plants plantts from the soil. This makes it easy for topsoil opsoil to be washed away by wind and water.r. When the th he e topsoil is removed, many plants and d animals cannot get the things they need d from the soil so that remains.

Soil can be harmed by pollution.

Soili pollution poll occurs when harmful things, ngs, such su as chemicals and rubbish, are added ed d to to soil. s il

Think Deeply How can water pollution affect land and soil pollution?

45

Science Words

Re ga le du ca tio n

Use the words to complete the sentences. minerals rocks magma igneous rocks

1.

volcano lava sedimentary rock metamorphic rock

rock cycle cle soil humus weathering eathering

Molten rock beneath the Earth’s surface is called d

.

is the breaking down of rocks into o smaller pieces. p

2.

3.

The part of soil that is rich in the remains of dead organisms is called o .

4.

On Earth, rocks are continually forming, weathering and changing form weath in a process called the .

5.

d sedimen Rock formed when igneous and sedimentary rocks are subject to heat . and pressure are

6.

Layers of sediment press together ogether to form

7.

is an opening openin in the Earth’s surface through which A magma flows as .

8.

All

9.

.

are made up of one or more minerals.

are non-living non-liv substances that are formed naturally in

the Earth.

10.

11.

46

form orm when magma or lava cools and solidifies.

is a mixture of weathered rock, minerals and other living non-living things. and non-liv

12.

Use the words in the box to label the soil layers. weathered rock particles subsoil

Re ga le du ca tio n

bedrock topsoil

(a)

(b)

(c)

(d)

Review

1.

List two minerals and how they are used by people. d describe desc

2.

ys people use rocks.

Describe two ways

3.

What is weathering? athering?

4.

sho how rocks change form during the rock cycle.

Draw a diagram to show

5.

How is humus different from subsoil? d

6.

w does soil so form?

How

7.

Describe Describ two ways people use soil.

8.

List two ways we can care for soil.

47

In the Field

Geologists

ati o

A geologist is a scientist that studies rocks, minerals, landforms and the processes that shape the surface of the Earth. They help us gain a better understanding of how rocks and minerals form and where they can be found in different parts of the Earth.

The data gathered and interpreted by geologists helps us to understand how the e surface of the Earth changes over time and and how how landforms landforms such such as as volcanoes, volcanoes, canyons canyons and and mountains mountains form form and and change. change.

48

Rocks and minerals are used by p people eople in many ways. Geologists observe and erve a nd test different rocks and minerals errals to to ffind in d new materials.

Some geologists study e earthquakes arthquakes and volcanoes and can help an even even h elp us us to predict when an earthquake arrthquake may may occur or when a volcano o may may erupt. erupt.

Geologists spend off time end a llot ot o time in nature collecting samples amples tto o sstudy. tudy So if you like the outdoors and ors a nd want want to to learn more about the off tthe he surface surf rface o h Earth, you’d love being a g geologist eologist – iitt rocks! eo

49

Weather and Climate

n

9

How can we describe and measure the weather?

How does the weather change between seasons?

50

In this chapter you will ...

ca tio

• collect and represent data to describe typical weather conditions.

anges • understand and describe how weather changes between seasons.

• describe climates in different regions of the world. ed hazard. hazar • design a solution to a weather-related

Go Online!

R

Access interactive content relating to this topic on the NGScience website. ngscience.com

How is climate different from weather? How are climates different we in different regions of the world?

51

Understanding Un n Weather The Earth is surrounded by a layer off air called T ca the th atmosphere. Weather on Earth th is caused by b the heating of the air in the lower ower part pa of the atmosphere by the Sun. un. The heating heat and cooling of the air causes it to move mo in different ways. Thiss movement of air is called wind. Air also contains wa water in the form of a gas called water vapor. vapo The heating and cooling h g of air causes cause the water vapor to condense into va nto clouds. clouds This can cause ca c au it to rain or snow. snow

ed

Weather is always changing. The weather in the We eat ys changing morning may be morn mo e different from the weather in the afternoon. a noon. Weather changes from day to day and from season to season. Weather is also different in different places.

AB

52

Activity A ctiv 9.1

Measuring Weather

ed uc ati on

How does the weather change from day to day? How can we measure weather?

By using different instruments and technology, we are able to accurately describe and predict weather. We can measure and predict temperature, the strength and direction of wind, or when it will rain. We are also able to predict extreme weather events like thunderstorms and nd hurricanes.

Temperature

Temperature is a measure of how hott or cold the air around us is. It is measured red in n o degrees Celsius ( C) or degrees Fahrenheit hrenheit renheit (oF).

Temperature is measured using a thermomete thermometer. hermomete When the temperature is high, gh, the he weather can be described as warm or hot. When Whe the temperature is low, the weather ather can be described as cool or cold. old old.

thermometer

53

Think Deeply The summit of Mount Everest is almost 9,000 meters. How would the air pressure at that height compare to the air pressure on the ground?

Air Pressure and Wind Like all matter, the air in the Earth’s atmosphere osphe has mass. Air pressure is caused by the th he weight eiight of the air pressing down on the Earth’ss surface. surf In lower areas of the Earth’s surface s ace there re e is more air pressing down than n high hig gh areas. areas. So S air pressure is higher at sea level and evel a nd decreases de with height.

Air pressure changes wit with When th temperature. tempe the heat from the Sun n heatss the he surface of the Earth, the air surrounding is heated. un ndi the the Earth E o rise and an the air pressure This causes the air to decreases.

The weather ather changes cha anges as the air pressure in an area changes.

Generally, low air pressure will nges. Gener result in bad bad weather weath such as strong winds and rain. High is associated with calmer igh air pressure pres weather atherr with w th clearer skies and little wind. re essure e is measured using a barometer.

Air pressure

baro ometer omet er barometer

54

wind sock

e Wind is moving air. When the heat from the Sun warms the air in one area, the air rises and and the air pressure decreases. In places where the th air is cooler, the air falls and the air pressure e increases. Wind is caused when air moves from an area of high pressure to an area off low pressure. The greater the difference ence in air pressure, the stronger the wind.

anemometer

We can measure the speed of wind d using an n anemometer or a wind sock. These can ese tools ca also be used to measure the direction rection tthe wind is blowing.

55

A Closer Look

du ca tio n

Sea Breezes and Land Breezes A good example to help understand the relationship between temperature, air pressure and wind is to look at sea breezess and land breezes.

R

During the day, the Sun heats both the land and ocean, but the land gets heated faster. This causes the air above the land to become warmer than the air above the ocean. The air above the land rises and the he e cool air from the ocean moves to take its ts place. This causes wind to blow from the ocean to the land. This movement of the air is called a sea breeze.

During a sea sea breeze, se br wind blows from the ocean onto land.

56

du ca tio

near-shore wind farm

Did You Know?

Wind farms are often located near the coast.

They use the energy in sea breezes and land breezes to generate electricity.

R

During the night, there is no Sun in the sky to warm the surface of the Earth. Both the land and the ocean begin to cool. The land cools down wn faster than the ocean. The warmer air above bove the ocean rises and the cooler air from the land moves to takes its place. This causes the wind nd to blow from the land to the ocean. This his movement of the air is called a land breeze.

During a land land breeze, la b wind blows from the land to the ocean.

57

Precipitation Precipitatio ecipitati Think Deeply

The air T he a ir in i our atmosphere contains water of a gas called water vapor. iin n the the form f When W he warm air rises, it begins to cool and tthe he water vapor forms tiny water droplets iin clouds. The droplets attach to dust and other particles. As more water droplets form and combine, they form larger drops.

The drops fall to Earth as rain.

Re ga

Earth is the only known planet to contain water in three states. What are these three states and where can they be found on Earth?

Water W ater that that falls fal from clouds in the sky is called precipitation.

There are four main ca alle lled p reci types – rain, sleet, snow ess of of precipitation p and a n hail.

58

sleet

In very cold temperatures, falling rain may freeze into small pieces of ice before reaching the ground. This type ype of of precipitation is called sleet.

If the air in the clouds is cold enough, enough, the the water vapor can rapidly freeze ee eze and and form form orm snowflakes. Snowflakes fall alll to to the the he ground groun as snow. hailstones

Re ga

During a thunderstorm, raindrops in storm orm, raindrop raindr clouds can freeze e to form forrm balls ba alls of of ice. i These balls of ice as hail. ce fallll to the ground gro How is rain ain different differe from sleet, snow hail? ow and hail

AB Activity 9.2

59

A Closer Look

The Water Cycle Water on Earth is constantly being heated and cooled. As this happens, water moves in a cycle between the surface of the Earth and the atmosphere. This process is called the water cycle. condensation condens onden The heat from the Sun causes the water in the ocean, lakes and rivers to change into a gas called water vapor. This process of changing from a liquid to a gas is called evaporation.

The water vapor in the air cools as itt rises and changes to liquid water in the e form of tiny water droplets in clouds. s. This This process of changing from a gas to a liquid is called condensation.

evaporation evap porat ation on

60

AB Activity 9.3

precipitation

Try This!

How long does oes it take for vaporate outside? out water to evaporate nduc an Plan and conduct igation to find out. investigation Whatt factors affect the rate af of evaporation?

ca tio n

The water droplets combine with other water droplets and eventually fall back to the surface of the Earth as precipitation. The precipitation flows on and under the ground into rivers, lakes and the ocean.

Go Onli Online!

Watch the water cycle in action cti in a video on the NGScience website.

NG QuickCode: C4D6

61

Weather satellites atellit orbit the Earth collecting collecti and sending din weather we eat a her information formation back to t Earth.

Weather Forecasting Weather scientists, called meteorologists, gists, ar are re constantly co using technology to gather information tion about the weather. Weather stations all over the collect data he Earth c on temperature, the movementt of wind, air pressure and precipitation. Buoys in the ocean an collect data about currents, water temperature and wave height. Ra Radars collect data about the movements of c clouds and precipitation. In space, weather satellites are constantly nstant orbiting the Earth, collecting and sending information the weather back to Earth. ion about th

62

Meteorologists use powerful computers to analyze and interpret weather information. By observing patterns in the weather, they are able to predict what the weather will be like in the future. These predictions are called weather forecasts. Weather forecasts are very helpful to people. They can help us to plan our day or week. They can also warn and help us to prepare for severe weather events, such as thunderstorms, hurricanes, floods and droughts.

Weather radars are able mov to monitor the movement ecipit of clouds and precipitation.

AB Activity 9.4

uc

What information do meteorologists communicate to people during a weather forecast?

l

Meteorologists analyze and interpret hatt ha patterns in the weather to predict what the weather will be like in the future.

63

Extreme Weather Go Online!

A supercell is a large rotating thunderstorm with an updraft of wind in the center. Supercells often have very strong winds, frequent lightning and very large hail. Find out more about supercells on the NGScience website.

QuickCode: P4N6

64

The weather can be different in many y ways.

One day it may be warm and sunny. y. The next day it may be rainy or windy. Occasionally, casionally, uring a there may be thunderstorms. ms. During thunderstorm there are often ften strong winds, win heavy rain and lightning. g. Thunderstorms Thunderstorm are an example of extreme treme me weather. weather Other extreme weather events hurricanes, ventss include hu hur tornadoes, floods and blizzards.

A hurricane is a rotating otating storm that forms over the ocean onto land. an and nd moves o Hurricanes have ve very strong stron winds and precipitation. tion. Hurricanes rrican often include a series of thunderstorms. derstorms. The heavy precipitation and large coastal astal waves can c also cause floods.

c

A tornado is a rotating column of air that occurs on land, often during a thunderstorm. m.

There are very strong winds. Due to the strong trong g upward movement of air during a tornado, ado, there is little or no rain. However, precipitation pitation tion can fall in the form of hail stones.

A blizzard, also called a snow storm, orm, m, is a w, sleet and cold winter storm with heavy snow, strong winds. Snow may completely mpletely ly cover roads and buildings.

Engineer It! Draw a model of a house that can withstand the impact of a thunderstorm. Label and explain how each part helps withstand the storm.

Re ga

Extreme weather can be dangerous gerous to people and cause damage amage mag to property. ope Engineers and architects hitectss often ofte design buildings and structures uctures ures to protect prote people against severe weather. ther.

AB Activity vity 9.5

Discuss cuss extreme w weather events that at occur in your you area. What are some ways people reduce the impact o of extreme weather?

65

ed uc ati o

The United States is in the Northern Hemisphere. In June, it is summer.

New Zealand land and is in the South Sout Southern Hemisphere. ere. re. In June, it is winter. w wi

Weather and nd d Seasons Seaso

Go Online!

Observe how the Earth’s tilt and revolution around the Sun cause us to experience seasons on the NGScience website.

QuickCode: R4S7

Summer

The Earth is divided ed into nto two hal halv halves – the Northern Hemisphere sphere ere and the Southern e Earth revolves rev re Hemisphere. As the around the ht hitss one hemisphere hemis Sun, sunlight more directly er. This causes caus cause us to experience than the other. seasons. example, the Northern s.. In June, for ex exa sphere ere is tilted toward to Hemisphere the Sun and is in mmer. The Southern South Sout summer.

Hemisphere is tilted away om the he Sun and is in winter. from

Northern Hemisphere

Winter

Southern Hemisphere

66

summer mer

Re ga le du c

Fall is the season after summer. During fall, the temperature gets cool and the number of daylight hours begins to decrease. The leaves on some trees begin to change color and fall away. This will help them to save energy during the approaching winter.

tio

Summer is the hottest season, occurring between spring and fall. Summer is the season with the most hours of daylight.

It has the earliest sunrises and the latest sunsets.

During winter, the Earth is tilted away est from the Sun. The weather is the coldest Su and the days are the shortest. The Sun rises later in the morning and setss in the late afternoon. In some partss of the n when n it Earth, winter is also the season round nd may is most likely to snow. The ground d streams stream be covered in ice and lakess and may freeze. Some animals become ecome come inactive or migrate to warm warmer places war aces during winter.

As winter moves to spring, number pring, the numb nu of daylight hours rs increases ncreases and the temperature getss warmer. Sp Spring is the season for reproduction. regrow oduction. Trees Tr their leaves flowers. es and start to produce prod pro Animalss become come active and an also reproduce spring. duce during sp

fall

winter

AB Activ A Activity 9.6

spring

67

A Closer Look

Graphing Weather Scientists are constantly collecting data about the weather.

They often create tables and graphs to help them understand nd seasonal changes in weather. Tables and charts are also useful so a u se way to communicate weather information to people.

uc a

Let’s take a look at the yearly changes in weather for San Francisco, United States.

Average Daylight Hours – San n Francisco Francis Jan Feb Mar Apr May Jun 10

11

12

13

14

14.5 5

Jul Aug Sep Oct Nov Dec S

14.5

13.5 13

112.5

11.5

10

9.5

Average vera Precipitation verag cipit i i – San Francisco 120 mm

Re ga

100 mm 80 mm 60 mm

m 40 mm 20 mm 0 mm

Jan

68

Feb Mar Apr May Jun

Jul

Aug Sep

Oct Nov Dec

ati o

How ow does the weather throughout the change thro year in Sa San Francisco?

um m Temp Average Maximum Temperature – San Francisco 25oC

al

20oC 15oC 10oC 5oC Jan J Ja n

Mar Apr May Jun Feb Mar

Jul

Aug Sep

Oct Nov Dec

R

0oC

AB

Activities 9.7 – 9.8

69

Climate

Re ga le du ca tio n

Go Online!

Climate describes the typical weather her in a region over a long period of time. The e equator is an imaginary line that runs through center rough gh the cente ce of the Earth. The climate in a region on depends on its distance from the equator or along with other oth o factors such as rainfall, elevation evation or distance distan from the ocean.

Watch videos on the Earth’s different climates on the NGScience website.

QuickCode: D3A2

Northern Alaska is far from the he equator. quator. The climate c is very cold and dry. Most precipitation on falls as snow. sn

The Amazon Amazo Rive River Basin is close to the equator. It is warm and wet w all year round.

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Re ga le du ca tio n

The climate in different regions can be different in many ways. Scientists often describe a climate by its average temperature and precipitation at different times of the year.

Describe the climate in your area. How does the climate change throughout the year?

The he Egyptian Egyptia d desert has a hot and dry climate.

The Antarctic region is very far from the equator. It is very cold and dry all year round.

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Tropical Climates

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Tropical climates are close to the equator. quator. tor. The Th temperature is warm and does not ot change hange much throughout the year. Precipitation cipitation on is high h all year round too.

Think Deeply What types of precipitation fall in tropical climates?

Explain your answer.

Generally, tropical climatess do not have four fo distinct seasons. Instead, they wet season hey have a we w and a dry season.

Many of the world’ss rainforests nforests are ar located in tropical climates. Being all year tro tr ng wet and warm w round, tropical rainforests ro ou forests are tthe most diverse land la an habitats on Earth. rth Wh don’t tropical climates Why experience four seasons? ex

A tropical rainforest in Thailand.

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k in a temperate tempera A park climate winter. e during winte

A park in a temperate climate during summer.

Temperate Climates

c

Temperate climates are located between tropical climates and the Earth’s poles.

Temperate climates usually have four seasons ons – summer, fall, winter and spring. The temperature perature can change a lot from day to day and also from season to season. It is hottest in the summer ummer and coldest in the winter.

al e

Precipitation is lower than in tropical climates, but pical climat it may rain throughout the year.r.

How are temperate erate climates different from tropical climates? pical c

Did You Know?

Compared to tropical climates, the weather in temperate climates can vary a lot from day to day.

It may be hot and sunny one day, then cloudy and cold the next.

A temperate climate during fall.

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Continental Climates

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Continental climates are climates located cated ed far from the ocean and usually in temperate mperate rate areas.

The temperature in continental climates tes follows the seasons. It is often very hott in summer and an cold in winter.

Precipitation is low and often during en occurs du dur summer. During winter, r, it may get cold enough for precipitation to fall all ass snow.

Coastal oastal astal C Climates

Coa Coastal Co climates are located close to the ocean, between a mountain range and the coast. often be Differences in air temperature cause wind and Differe Difference rain ain to m move in a pattern between the ocean the land. This results in a climate that is cool and th an and wet.

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Alpine Climates

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The height of an area above sea level affects its climate. Generally, the higher above sea level, the colder the temperature. Alpine climates, also called mountain climates, are often cold all year round. It is often much colder at night compared to the day. Mountains have little soil and the ground is often covered in ice or snow. Generally, trees cannot survive in alpine climates.

Polar Climates

Polar climates are cold old all year yea round. There are cool summers and very cold winters.

There w are few trees and covered d the e ground is often o in ice. Polar regions heat and ons do o not get direct direc d sunlight from the Sun. There are long days a very v in summer and very short days in winter.

Did You Know?

The Earth has two poles – the North Pole and the South Pole.

The region surrounding the North Pole is called the Arctic.

The region surrounding the South Pole is called the Antarctic.

AB Activity 9.9

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ga le du ca Climate Change hange

Climate change describes the ways in which the Earth’s climate mate changes change slowly over time. he Earth’s climate has been In the past, the colder and hotter than it is now. Scientists have red that human hum activities, mostly the discovered burning of fuels, are a causing the climate to get fas than normal. hotter much faster increas in temperature is causing ice in Thiss increase the Earth’s polar regions and glaciers to melt faster than normal, leading to rising sea levels..

These The changes are affecting living things and people peop in many ways.

As A the sea level rises, coastal areas around the Earth are at risk of flooding. Scientists have also discovered that hotter temperatures are causing more extreme weather. There are longer droughts and floods, stronger hurricanes and bigger wildfires.

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How will the melting of polar ice sheets affect the animals that live there?

Many plants and animals may not be able abl to adapt to the changes caused by y climate change. Those unable to adapt are e at a greater risk of becoming extinct.

AB Activity 9.10

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Science Words

Re ga le du ca tio n

Use the words to complete the sentences. atmosphere water vapor temperature thermometer air pressure barometer

anemometer precipitation water cycle evaporation condensation meteorologist

1.

Rain, sleet, snow and hail are forms of

2.

Air pressure is measured using a

3.

weather forecast ecast seasons mat climate uator equator mate change chang climate

.

.

describes the typical al weather in a region over a long period

of time.

4.

is a measure of how w hot or cold c the air around us is.

5.

Air contains water in the form orm of a gas g called

6.

The

7.

A prediction of what will be like in the future is called at the weather wea a .

8.

The of the Earth. h.

9.

A

10.

is c caused by the weight of the air pressing down on the surface.

Earth’s surf

11.

is the movement of water between the surface of the The Earth and the atmosphere. th a

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.

is a layer l of air that th surrounds the Earth.

is an im imaginary line that runs through the center

is is an instrument inst used to measure temperature.

is the ways in which the Earth’s climate changes slowly

12.

Re ga le du ca tio n

over time.

13.

The process of changing from a liquid to a gas is called

.

14.

The process of changing from a gas to a liquid is called

.

15.

is a scientist that observes and makes akes predictions prediction about A the weather.

16.

are weather patterns caused by the he revolution of the Earth around the Sun.

17.

Wind speed can be measured using an

.

Review

1.

List three elements of the weather her that we can c measure.

2.

True or false. e lower the air a temperature. (a) The warmer the air, the blow from the ocean to the land. (b) During a sea breeze, wind blows (c) During a land breeze, wind blows blow from the ocean to the land.

3.

What is hail?

4.

What happens when water wate evaporates?

5.

eather forecast? forec What is a weather

6.

e types of extreme extre List three weather.

7.

se What causes seasons?

8.

What is the difference between weather and climate?

9.

a humans contributing to climate change?

How are

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A Closer Look

The Greenhouse Effect In a greenhouse, heat from the Sun passes through the glass and heats the air inside. At night, when the temperature drops, the glass walls and roof trap some e of the heat inside keeping the greenhouse warm. A similar ila thing happens when the Sun heats the Earth.

When en the heat from the Sun warms the Earth, rth, gases in the th Earth’s atmosphere, called alled greenhouse greenhou gases, trap some of the heat in the Earth’s atmosphere. This is called d the greenhouse effect.

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Some of the heat from the Sun is reflected back into space.

Greenhouse gases trap heat inside the Earth’s atmosphere.

Go Online!

Learn more about the th se effect and greenhouse cts the Earth in how it affects mated video on the an animated NGScience website. cience web QuickCode: M6P4 QuickCode M6

tio n

Greenhouse gases such as water vapor, carbon dioxide and methane occur naturally in the Earth’s atmosphere. However, the burning of fuels is causing an increase in the amount of greenhouses gases in the atmosphere. This is causing an increase in the average temperature on Earth.

How are the greenhouse effect and climate change related?

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States of Matter

du ca tio n

10

In this chapter you will ...

• describe matter and its states.

• describe the properties of solids, liquids and gases.

• describe how matter changes when it is heated. cooled • describe how matter changes when it is cooled.

What are the properties es o of solids, liquids and gases??

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ed uc ati on Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

How does matter change when it is heated and cooled?

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What Is Matter?

Try This!

Find five objects in your classroom. Pick up each object and order them from the least to the most mass.

Use a balance to check if you were correct.

Think Deeply

Mass is how much matterr an object has. Mass is measured using a scale ale or balance and an is ograms, grams, gr commonly measured in kilograms, ounces or pounds.

We can compare matter e the e mass of different d using a balance. shows that e. The he balance below b the boot has more mass than tha the shoe. The plastic ball and the apple are a of similar size.

Using a balance we can see that the apple has a greaterr mass. mass

Re ga l

Chelsea placed two boxes of different sizes on each side of a balance. She noticed that the balance remained level. What can she infer about the mass of the boxes?

du ca tio n

Everything around you is made of matter. ter. The air you breathe, the water you drink and even this nything that tha book is made of matter. Matterr is anything has mass and volume.

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Volume is how much space the matter takes up. The basketball, beach ball and d tennis ball all contain matter – air. The e amount of space the air takes up in n each ball is different.

Volume can be measured using ing measuring easuring cups, measuring cylinders or measuring spoons. Volume is commonly nly measured in i milliliters, liters, gallons and ounces. nces. ces.

Which beaker contains the th greatest volume of water? ater? How can ca you tell?

Order tthe balls from the smallest smalles alle volume to the greate volume. greatest

Think Deeply

Using a measuring cup and water, how could you measure the volume of the air inside a ping pong ball?

AB

Activity 10.1

85

States of Matter There are three states or forms of matter ter – solids, liquids and gases. The properties perties es of each state of matter is different.

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Try This!

Find a solid object in your classroom. Use your senses of sight and touch to describe the object to a classmate.

The pencils stay the same shape whether they are in the cup or the pencil case.

What are the properties rties of solids, liquids and gases? ases?

Properties of Solids ds

The objects around you, desk, u, such as your yo y books and pens are solids. ids. Solids are matter that have a fixed shape volume. This means the ape and volume shape and volume does not change lume of a solid d when it is placed aced d in different containers. If you take a book between different ok and move it b containers, ers, its shape an and volume does not change. e.

A rock is an example of a solid. Take a small examp exam rock ock and place it on a hard surface. Use you foot to press ress down dow on the rock. Notice that pressing down wn n on the rock does not change its shape or volume. v e. Solid e So matter cannot be compressed and doe does oes not change shape easily.

AB A

836

Activities 10.2 – 10.3

Properties of Liquids Water, milk and cooking oil are examples of liquids. Like solids, liquids have a fixed volume.

This means the amount of space taken up by a liquid always stays the same.

Try pouring some water into a measuring cup and measure its volume. Pour the water into a measuring cylinder and measure its volume again. You’ll notice that the volume of the water does not change when placed in different containers. Like solids, liquids cannot be compressed.

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Unlike solids, liquids do not have a fixed shape. The shape of a liquid depends on the container it is in. When your pour some milk from a carton or bottle into a glass, the shape of the milk changes, but the volume of the milk remains the same.

In what ways ys is a liquid different from a solid? solid

Try This!

Use containers of different sizes to demonstrate how a liquid flows to take the shape of its container. How can you find out if the volume of the liquid changes?

4 87

erties of o Gases Properties Gases es are matt matter that can change in both shape ape and volume. You can’t always see gases, butt they are all around you. The air you breathe is a gas. Th The water vapor released from a boiling kettle is also a gas.

Re ga

When you blow up a balloon, you are filling the Whe balloon with air from your lungs. You can press ba ssoftly on the expanded balloon and change the shape of the gas inside. When you let go of the balloon, the gas spreads out in all directions and fills the room. Its volume changes.

Think Deeply p

What will happen to the th shape and volume of the on when air inside a balloon the balloon is popped?

We can also compress a gas to reduce its volume, like when adding air to a scuba tank.

Inside the scuba tank, the compressed air takes up much less space.

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le du

Use the pictures to compare e and contrast the properties of the different states of matter.

AB Activity 10.4

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ca

Heating Matter

There are e three states of o matter – solids, liquids and gases. es. Matter can change from one state to another when heat hea is added or taken away.

Melting elting When is heated, it changes from en solid matter m a solid to a liquid. Ice is a solid. When ice is heated it changes into liquid water. This process he changing from a solid to a liquid is called of cha melting. melti A candle is made of solid wax. When you light a candle, the heat from the flame causes the solid wax to melt into liquid wax. w What are some other examples where heat causes a solid to melt into a liquid?

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Evaporation

du ca tio n

How will liquid matter change when it is heated?

When liquid matter is heated, it changess into into a gas. This process is called evaporation. n.

When it rains, puddles of water form on the ground. As the heat from the Sun warms the water, the puddles get smaller. A puddle gets smaller because the water evaporates into the air as a gas called water vapor. Eventually, all of the water evaporates into the air and d the puddle dries up.

When water is heated to a high temperature, it boils. The bubbles you see ou se ee e in s. The e a pot of boiling water are pockets off ga gas. face of tthe he e water w bubbles of gas move to the surface and into the air as water vapor..

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ga le du ca tio n

Think Deeply Where do the water dew droplets on grass come from?

What causes them to form?

Cooling oling M Matter

How does matter change when it is cooled? whe

Condensation Con Cond

Have you ever noticed water droplets form on the side of a cold glass of water? The droplets water form when water vapor in the air cools of wa as it comes in contact with the cold glass. This p pr process of changing from a gas to a liquid is called condensation.

The water droplets that form on a mirror after a hot shower and the dew on grass on a cold morning are other examples of condensation.

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Freezing What change will occur when water is placed in a freezer?

du ca

Pour some water into an ice tray and place it in a freezer. After a few hours,, you’ll notice that the liquid water has changed into solid ice. This process of changing from a liquid to a solid is called freezing.

Chocolate melts when it is heated in a pan. The liquid chocolate flows and can be poured into molds. When the liquid chocolate freezes, it becomes a solid with its own rigid shape.

AB Activity 10.5

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Science Words

Re ga le du ca tio n

Use the words to complete the sentences. matter mass volume solid

liquid gas melting evaporation

water vapor condensation freezing

1.

is the process of changing from a solid to a liqu liquid.

2.

is the amount of space matter takes up. u

3.

is the process of changing from om a liqu liquid to a gas.

4.

matter has a fixed volume, me, but can ca change in shape.

5.

A

6.

How much matter an object has is its

can change in both th shape and an volume. .

7.

is anything that at has mass ma and volume.

8.

matter er has a fixed shape and volume.

9.

Water in the form m of a gas is called

.

10. The process of changing from a gas to a liquid is called

11.

The processs of changing changin from a liquid to a solid is called

Review ew

1.

What is mass and how can it be measured?

2.

How can you measure the volume of a liquid?

94

.

.

Create a chart to compare the properties of solids, liquids and gases.

Provide an example of each state of matter.

4.

en tthe Describe what happens to the volume of air in a balloon when balloon bursts.

5.

re.

Describe the processes taking place in each picture. (a)

(b)

c) (c)

du ca tio n

3.

Re g

(d)

6.

change takes place when melted chocolate is cooled?

What chang

7.

What change takes place when butter is heated in a pan?

8.

What change takes place when water vapor cools on a cold glass?

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11 Interactions and Forces In this chapter you will ...

• describe the ways in which forces affect motion.

• distinguish and name contact and non-contact forces forces.

an magnetic • determine cause and effect relationships off electric and ntact with each e interactions between two objects not in contact other.

lved by applying ap • define a simple problem that can be solved knowledge of magnets.

balanc and unbalanced forces • provide evidence of the effects of balanced on the motion of an object. nd motion to predict motion.

• use knowledge of forces and

How can you telll that an object is moving? What to move? at causes things thi

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ed u

What is a force? How do we interact with forces in daily life? fe?

Go Online!

Access interactive content relating to this topic on the NGScience website. ngscience.com

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Position and Motion Position Look at the objects in the room below. w. How can you describe the location of the he teddy eddy bear?

Try This!

You can say the teddy dy bear ear is on the table and to the right of the spinning other pinning ing wheel. What W words can you use the se to describe th t position of the teddy bear?

du c

In small groups, take turns in describing the positions of objects in your classroom. The first person to guess the correct object is the winner!

When you tell where something ething hing is, you describe des de its position. Position is the e location of something. som

With a partner, artner, take ta turns to position of the describe the po other objects in the room.

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Distance and Direction

du ca tio n

We can more accurately describe the position of an object by describing its distance and direction.

Distance is a measurable amount of space between one object and another. You can measure distance using different units. For objects that are close to each other, you can use units such as millimeters, centimeters and inches.

Go Online!

Learn more abo about position, distance and direction on NGScience website. the NGScie QuickCode: uickCod E9V8

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For objects further away, you can use meters, feet and yards. For even further distances, you ou can use kilometers and miles.

Direction is the course one se or line from fr o object to another. You u can n use words word such suc as left, right, north, south, east direction. st and west to t describe de

By using both you can h distance and direction, d describe accurately. be position osition accurate

The green car is two centimeters behind the orange car.

Try This!

Describe the position and direction of your house to your school.

My hous house is two kilometers north of my m school.

AB

Activity 11.1

99

Describing g Motion Look at the skier kier in in the the picture. pictur pictur How does the position of the he skier skier change? chang change We know w thatt something somethi somethin has moved when it has changed position. When something is hanged positio in the position, we say it e process ro ocesss of of changing ch is in can describe and measure n motion. motion tio . W We ec different motion ion in differe difffere ways.

1 00

uc a

With a partner, compare the motions of the people and objects on these two wo pages. How are the motions different??

The skier is in motion mo on when he is in the he process proc pr ce of o changing position. sittio ion. n.

1 01

Go Online!

With a partner, go to the NGScience website and watch the ‘Describing Motion’ video. Take turns to describe the motion of different objects.

QuickCode: S7Q7

ed u

We can describe scribe e motion in many ways. A bowling ballll moves in line towards the i a straight st pins. On back and forth. n a swing you move m What’s you your favorite ball sport? words can you use to What wo describ describe the motion of the ball?

1 02

du ca

Think about the different things in a playground. How can you describe re your motion when you play on different equipment?

On a swing, you move back and nd forth. On O p and down. wn. On a a seesaw, you move up carousel, you move round und and a round.

Activity 11.2

ga l

AB

A downhill skier moves from side to side in a zigzag motion.

What are some other ways we can describe motion?

1 03

Measuring Motion

ga le du ca tio n

Like describing the position of an object, bject, t, we can use distance and direction to describe cribe and measure motion.

An airplane travels about 3,200 200 kilometers in i an easterly direction to fly from rom San Francisco Franc to Denver.

Try This!

The fastest man on Earth can run 100 meters in less than ten seconds!

Time how long it takes you to run 100 meters. Compare your time with your friends.

Use distan distance and direction to describe your motion as you get from your home to your school.

You can an also use time to describe motion.

Time is how long it takes for something to move T Tim from one on position to another. You can measure time using seconds, minutes and hours. u

AB

104

Activities 11.3 – 11.4

ca

Compare the motion of the bicycle and the e motorbike. How is the motion different?

The motorbike is moving much fasterr than than the bicycle. How fast or slow something thing g moves is its speed. We can measure sure ure e speed spee ed by calculating the time it takes an object ect to cover a certain distance.

Think Deeply T

It takes an airplane about two hours to fly from New York to Chicago. It takes a train about 20 hours to travel the same distance.

Which moves at the greater speed? How do you know?

If a cyclist rides 30 kilometers hour, ters in one hour ho we can say the speed of the he cyclist was was 30 wa kilometers per hour.

Activity 11.5 1.5

al

AB

1 05

tio n

The tennis player yer usess push forces to throw hrow and d hit the ball.

What Is a Forc Force? ce Pushes es and Pulls Pull

Whenever never an object objec is in motion, it is because on the object, cause e a force acted ac causing move. A force is a push or ausing ng it to mo mov a pull. when you press something A push is w away from fro you. You use a push when jump in the air. You use a push you ju jum when you throw or hit a ball. The push force starts the ball moving. forc

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A pull is when you tug something omething closer to you.

You ou use a pull when you open pen a drawer or drag a suitcase.

The he pull causes the objects bjects to move.

R

There can be be more mo than one force acting ac cting on an object. When n you use a bow and arrow, arrrow you push and pull att the same time.

1 07

n

How are forces used to move the golf forc ball differently? What effects do forces olf ball? have on the motion of the golf

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Forces can an nh have ve dif different strengths.

A large, will move an ge e, strong ng force fo obje ect ffurther urther a object and faster than a malle er, softer s fte force. smaller,

1 08

c

Compare the logs in the truck to the tree in the cart. Which would require a greater force to move? Why? Larger, stronger forces are required to to move move heavier objects.

e truck truck is is much much The force required to move the red d to to pull pull the the cart. ca greater than the force required

AB

Did You Know?

We can measure the strength of a force using ng a spring balance called d a Newton meter.

Activity 11.6

1 09

Forces can affect ffect the motion mot on of objects in n different ways. ways way When a player ayer kicks the th ball off the e ground, round, it starts star sta the ball moving. ving.

Think Deeply

ga

How does the strength of a kick affect the distance the ball travels? Plan and conduct an investigation with your friends to find out. ut.

Communicate your findings ngs to other groups.

How do forces change the motion of a soccer ball during a match?

110

Players kick the ball as they run, moving g the t ball in a zigzag motion.

Passing the ball from player to player yer causes the ball to speed up, slow w down own and change direction.

R

To prevent a goal, oal, the goalkeeper per uses es a push force which h stops the motion on of the ball.

AB

Activity t 11.7

111

Contact Forces ces There are many different types off forces urr acting around us. Some forces occur hey are arre called called when objects are touching. They contact forces. eople, e e, animals and a Pushes and pulls from people, e of contact contac ct forces. fo forc machines are example e, the e pitcher is iin contact In a baseball game, with the ball when en he pushes it forward. ffo To change the direction ection of the ball, there is contact between een the bat and an the ball.

al

A tow truck needs to be in contact with the car to affect its motion.

112

R

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Judo is a contact sport.

Players make contact as they use pushes and pulls to affect each other’s motion.

Discuss the contact forces you observe in daily life. How do the ob contact forces affect motion?

1 13

Take a book and slide it along the cl classroom las floor. What do you observe?

When you slide a book, you use se a push push force to set it in motion. The book book slows slows down and comes to a stop due pd ue to to a contact cont co force called friction..

Friction is a force that at opposes opposes motion. mot It occurs when the surfaces off objects rub surfa rfaces o obj together.

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Rough surfaces more cess produce produce ce m o friction than smooth surfaces. rfacess. Friction Fric iction on is i also greater when surfaces harder together. rfa aces press pres ress har har

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Sometimes it is useful to reduce friction. A slide has a smooth surface to reduce friction. A snowboard has a smooth surface to help it move quickly on snow.

ca tio n Try This!

What are some examples of when it is useful to increase friction?

Have you ever seen s their hands someone rub th together ogether when it is cold?

What do you Try it now. W can you observe? What W about friction? infer abo

As a force that opposes motion, we can increase rease ease friction to help things to slow down or stop. is helps lps to The soles of shoes are often rough. This oe and the he increase the friction between the shoe ground and stops you from slipping. g. ds A bicycle has rubber brake pads to increase friction when it presses against the wheel rim. w This allows the cyclist to slow down or stop moving.

Activities 11.8 1.8 – 11.9 1

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AB

R

brake pa pads

1 15

uc at

Non-contact Non on-co -co ontact Forces Some So me force forces es ca can push and pull objects touching.

These forces can act without tou uch distance at a distanc ce and are called non-con non-conta ta forces. non-contact

Re ga

magnet on a piece of paper Place e a ma sprinkle iron filings over the and d sprinkl What do you observe? magnet. W ma

116

The pattern of the iron filings is the force. A magnetic result of magnetic m force can act a at a distance.

A magnet is an object with a magnetic force. A magnet can pull or attract objects made of certain metals such as iron and nickel. A magnet cannot j attract objects made of plastic, wood, glass. rubber or glass

eg al ed uc ati on

A magnet has two poles – a North pole and a South pole. When the like poles of two magnets are brought together, they push or repel each other. When unlike poles are brought together, they pull or attract each other.

Engineer IIt!

Design, mo model odel and a useful build a use eful ul tool that uses ma magnetic m force. orce. Describe Desc cribe how orks and the tool works how it usess magnetic force. mag

Like poles repel each other.

Go Online!

Unlike poles attract act each other.

Many objects make use of magnets. gnets. Some Som So doors used magnets to keep them hem closed. close A maglev (magnetic levitation) train tati tation n has magnets that repel it from the track. ack. This Th reduces friction and allows the train n to travel at fast fa speeds.

Magnets are also imaging and so used ed for medical med storing data on computer omputer disks. dis

A maglev train uses magnets to hover above the tracks. This allows it to reach speeds of more than 400 kilometers per hour!

Watch a maglev train in action on the NGScience website.

QuickCode: P8T1

AB Activity vity 11.10

magnetic levitation train

1 17

n

As the boy moves down the slide his hair stands on end! What force is causing this to happen?

Electrical forces are re e created creatted when there are unbalanced nced ced ele electrical ectriical charges inside an an object. object. harges ess rep ep pel each eac other.

Opposite charges repel Like charges each ge es attract tract eac h other.

The plastic astic slide slid caused cause us the boy to have e an an imbalance imbala balance ance of like charges in his in his hair his body. body. The The charges ch repelled other. The electrical re epelled elle ed each each ea h ot force forc rc ce was w wa as strong stro enough to make his hair air stand stand on on end.

118

Re ga le du ca tio n

You can create and observe the electrical force yourself.

Rub a balloon through your hair. Slowly pull the balloon away from your head. What do you observe?

Rubbing the balloon through hair created ough your yo y two opposite static charges. attract arges. The charges ch one another and make ke your hair stand sta up.

Notice that your do not our hair and the balloon ball need to be touching other. hing to affect affe each e Electrical forces are non-contact forces and can non-cont non-co act at a distance. ance.

AB

Activity 11.11 Activi

1 19

Think Deeply Gravity on the Earth’s moon is only one-sixth of the Earth’s gravity. With a classmate, talk about what it would be like to walk, jump and play different sports on the moon.

When skydivers jump out of an airplane, they are pulled towards the surface of the Earth.

What force is pulling them down? at pulls pullss on o All objects have an invisible force that gra ita ati n other objects. The force is called gravitational force, or gravity.

The strength stre e of an object’s gravitational force on it mass. Mass is the fo orce depends d amount of matter something is made of. a amo The gravitational force of objects with a T small mass, such as a basketball, is too weak to observe.

Compared to a basketball, the Earth has a much greater mass. The strong gravitational force of the Earth affects everything on its surface.

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Amazing Fact!

The object with the most m mass in our system is ur solar syste the Sun. The e gravitational grav force of the Sun keeps all ke of the e planets and a other bodies in the so solar system in orbit around it. it

ca tio n

It is the force of gravity that pulls you down when you jump in the air. It is the force that keeps everything on the Earth’s surface.

al e

Gravitational force also depends on distance.

The closer objects are to each other, the greater the gravitational force.

AB Activities 11.12 – 11.13 3

Think Deeply How does a parachute help a skydiver reach the ground safely?

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Think Deeply An object in space can remain in motion with no forces acting upon it. Explain why this is so.

du ca tio n

Balanced and Unbalanced an Forces In a game of tug-of-war, one team am pulls ulls the th rope in one direction and the other er team pulls pull the rope in the opposite direction. ction. What happens hap ha if both teams pull with the same ame force? What W happens when one team m pulls with a stronger str force than the other team? am?

When both teams use the same amount of am a force in opposite directions, cancel ctions, the forces fo each other out. They forces. ey are balanced balan When the forces orcess acting on an object are balanced,, there change in motion. ere is no cha ch

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du ca ti

To win a game of tug-of-war, one team must pull with greater force. The forces acting on the rope are not equal. Forces that are not equal and do not cancel each other out are re unbalanced forces.

When there are unbalanced forces acting ng on an object, there is always a change in motion. motion

The forces are unbalanced unbalance and there is chang in motion. a change

The forces are balanced and there is no change in motion.

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Balanced Forces In small groups, describe all of the forces acting on the soccer ball in terms of strength and direction.

Is the net force zero? How do the forces affect the motion of the ball?

Look at the picture of the boy holding ng the he soccer soc ball. Why is the ball not in motion?

tio n

Think Deeply

The forces acting on an objectt have ve both strength and direction. An object bject at rest typically typi ty has multiple forces acting on n it, but they add a to give zero net force.

When the boy holds the ball and presses it pre against hiss side, all of the on the e forces acting ac a ball results in zero o nett force and there is no change in motion. motio on.

ga le d

A soccer ball all on the ground is being pulled ulled d down by the th force of gravity. grravity. ravity. At the same s time, the he ground ground is exerting ex a push ush force forc orc ce in an equal ce e and The d opposite oppos ossite site direction. direc forces – there is orces es are balanced balan force zero o net fo rc – and the ball remains mains ains att rest. re

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Unbalanced Forces

ati on

Forces that do not sum to zero can cause changes in an object’s speed or direction.

When the boy kicks the ball, he applies a force greater than the force of gravity. This creates an unbalanced force and sets the ball in motion.

When there are unbalanced forces acting on an object, a change in motion occurs. Unbalanced forces can cause an object to: • start moving • speed up • slow down • change direction • stop moving

AB Activities 11.14 – 11.15 125

le du ca ti Predicting g Motion otion

You can use yourr knowledge nowledge of motion, the measurement of motion and forces to predict f future motion. n.

On a seesaw, people will saw, you can predict pr p move up p and down. On O a swing, you move back and d forth.

Use you your knowledge of motion, gravity and friction to predict the motion of a marble when it is dropped into a bowl. mar

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Think Deeply Thin

How are airlines able to accurately predict the time it takes to travel from one country to another?

You can use information about distance, ce, time me and speed to predict the time you will arrive at school – whether you arrive by car, ar, bus, walk or ride a bicycle.

Use se your y knowledge of motion and forces to mot predict the motion of a pr skydiver from the surface of the Earth, into the air and back down to Earth.

AB Activity 11.16

What are some other examples where we are able to predict motion?

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Science Words

Re ga le du ca tio n

Use the words to complete the sentences. force friction gravitational force position distance

rces contact forces ontact forces force non-contact magnetic force balanced alanced electrical forces

direction unbalanced motion speed time

1.

is the location of an object.

2.

is the measurable space between ween two objects. ob

3.

des The course or line from one abject to another describes

4.

An object in the process of changing anging position is in

5.

is how long it takes for something somet to move from one position to another.

6.

How fast or slow an object moves is its

7.

A

8.

Forces that occurr when objects are touching are called obje

9.

an act at a d Forces that can distance are called

10.

.

.

.

is a push or a pull.

.

.

occurs wh when the surfaces of objects rub together.

11.

gnet is an object objec with A magnet

12.

are a created when there are unbalanced electrical charges inside side an object. ob

13.

pulls all objects towards the center of the Earth.

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.

When the forces acting on an object are change in motion.

, there is no

Re ga le du ca tio n

14.

15.

When the forces acting on an object are in motion.

, there is a change

Review

1.

List the forces that cause a ball to slow down and d stop when it is rolled along the ground.

2.

Describe and provide an example of a contactt forc force.

3.

True or false. Friction is a non-contact force. ce

4.

List three forces that can act at a distance. nce.

5.

Why does a rocket need a large e force to lift iit into space?

6.

True or false. An object at rest with zero n net force acting upon it will remain at rest.

7.

Describe what happens to an object objec when the forces acting on the object do not sum to zero.

8.

Predict and describe motion of the children. What are the forces be the mo that cause the motion?

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A Closer Look

Magnetic Resonance Imaging (MRI) Did you know that magnetic force can be used to create images of the inside of your body?

Some hospitals have large donutshaped devices called MRI machines.

MRI stands for Magnetic Resonance Imaging. So how does an MRI machine use magnets to see inside your body? ugh Patients lie on a bed and move through the donut-shaped cylinder which contains very powerful magnets.. The magnetic force is turned on and nd off ff very quickly. Different parts of yourr netic c force body respond to the magnetic uter records in different ways. A computer n image o these changes and creates an of rga and tissue rgans the patient’s bones, organs tissues.

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MRI is very helpful. It allows doctorss to t diagnose problems by studying the e images without the need for surgery ery y or causing any pain to patients.

Go Online!

Watch an MRI in action on the NGScience website.

QuickCode: E5G1

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12 Forms of Energy In this chapter you will ...

• list and describe different forms of energy.

• explain how sound is made and how it travels.

erent • describe ways in which sounds can be different.

• list sources and uses of light.

• describe how heat moves and how heat is use used by people.

What is energy? How do people use energy in their everyday ryday lives?

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c

What are some different forms of energy?

Go Online!

R

e

Access interactive content relating to this topic on the NGScience website. ngscience.com

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What Is Energy? gy?

Did You Know?

Energy cannot be created or destroyed. It can be transferred or changed from one form to another.

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Everything that happenss around you y happens because of energy. You need energy to carry en ke breathin out daily activities like breathing, sleeping and playing sports.

Energy makes cars, bus buses and trains move. f Energy makes things feel hot, makes sounds and producess light.

All living things need energy to live n Earth and grow. Most of the energy on he comes from our Sun. Plants use the od energy from sunlight to make food.

The energy in the food made by plants is passed on to animals and people when they eat plants.

There are different forms of energy.

Some forms include sound, llight and hese forms o heat. People use these of energy ny different ways. and others in many

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Sound Engineer It! Musical instruments make sound when a part of the instrument vibrates. Design and build your own musical instrument using art and craft supplies. Form a ‘band’ with your classmates. Play a song!

ca tio n

What Causes Sounds?

What are some sounds you u hear from fro day to day? What causess the sounds? sounds We hear and make soundss all the time. We W make sounds when we talk, a lk, clap or play p musical instrument. Objects bjectss like cars, sirens, s ons make sound too. phones and televisions

Sound is a form of energy we can ca hear. All sounds are made vibrates. ade when something some Vibrations are re rapid apid id back and a an forth movements.

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uc ati o

When a bow is pulled across the strings of a violin, the strings vibrate and make sound. The vibrating strings cause the air around them to vibrate too. This creates sound waves. You hearr the sound when the sound waves travel through w gh the he air to your you ears.

Try T ry This!

A sound so is made when something vibrates. som Plan and conduct an investigation to show that sound can also cause an object to vibrate.

Did You Know?

When you throw a ball against a wall, it bounces back towards you. Sound waves travel in a similar way. When sound waves hit a surface, they bounce off the surface and move out in different directions.

You hear the sound that bounces back towards you as an echo. The echo is similar to the original sound.

AB

Activity 12.1

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Describing Sounds Use a microphone and computer to record loud and soft sounds. Observe the size of the waves produced. What do you notice? What happens to the waves when you move further from the microphone?

Go outside, close your eyes and nd listen to the sounds around you. How ow can c you describe the sounds your hear?

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Try This!

We can describe the soundss we hear in different diff di ways. One way to describe be e a sound is by its volume. Volume is how loud is. ud or soft a sound so The sound of an airplane plane ne jet engine and the sound of thunder are examples xamples of o loud sounds.

The rustle of leaves ves and a whisper whisp are examples of soft sounds.

A loud sound than a soft nd has as more energy en sound. Hitting with a large force creates itting a drum w wit larger vibrations brations and a louder sound than if it were hit with a smal smaller smalle force.

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ti

al ed uc a

Compare the sound of a rooster crowing to that of a lion’s roar. The volume of the sounds are similar – they are both loud sounds. However, ver er, they are different in pitch. Pitch is how high or low a sound is.

The crow of a rooster is a high-pitched sound.

The roar of a lion is a low-pitched sound. nd.

The faster an object vibrates, the higher igher gher the pitch of the sound. The length and thickness ckness ess of the vibrating object also affects its pitch.. You can see this by making different sounds ds on a guitar. gui guit A thin, short string producess a much higherhigher highe pitched sound than a longer, string. r, thicker hicker string stri

Go Online!

Did you know doctors can use sound waves to see inside your body? Learn all about ultrasound on the NGScience website.

QuickCode: M6U2

AB Activity 12.2 2

Engineer It!

Design a device that uses the volume and pitch of different sounds to send a message to another person.

How will you change the volume of the sounds? How will you change the pitch?

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The Sun is ourr main source of light.

du c

Light Sources and nd Uses of o Light

Amazing Fact!

Light is a form of energy that allows us to see the things around us. Any object that gives out ar light of its own ow is called a source of light. Some sources es of light, such as the Sun, lightning and fir fire are natural sources of light. Others, such as light bulbs and glow sticks are made by people – ight b are artificial sources of light. they a

a

The Sun is about 150 million kilometers from Earth. The light from the Sun takes about eight minutes to reach the Earth.

What are some sources of light? ight? How are sources of light ight used by people?

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ca t

During the day, the Sun is our main source off light. Plants use the Sun’s light energy to produce oduce ce food. This provides energy to people and animals nim mals when they eat the plants.

Sunlight also helps us to see the things ngs around us. At night, we often use lights to see. ee. Lights are a also used to send messages, such as telling cars ca when to stop and start at traffic lights.

Light is also used by people in devices ssuch as telephones, televisions and an computer puter monitors.

Re ga l

AB Activity 12.3 2.3

Think Deeply Light plays a very important role in boat navigation and safety. Lights of different colors tell people which direction to travel and warn them of danger. Boats are often required to display a raised, round, white light that can be seen from all directions. How is this useful?

1 41

Properties of Light Light travels out from a source off light in a straight line. It continues to travel straight line ravel in a straig until it hits an object.

We are able to see sources the es of light when w light travels from the source urce to our eyes.

We are also able to see objects that are not sources of light when en light rreflects or bounces off them and into to our eyes.

The Earth’s h’s moon is not a source of light. We are able to see ee the moon when it reflects the light from the Sun.

1 42

What things can you see around you? What source of light are they reflecting?

al ed uc a

Different surfaces reflect light in different ways. When light hits a dull or rough surface, such as a road, some off ht the light is absorbed or taken in. The light that is reflected bounces off in differentt directions. These surfaces appear dull.

ion

Most objects are not sources of light. We see them when they reflect light.

hat Other surfaces reflect a lot of the lightt that he same hits them. The light bounces off in the hiny. direction. These surfaces appear shiny. ht that A mirror reflects almost all of the light e to o see your hits it. That’s why you are able reflection clearly.

Try This!

Draw an object you can see in your classroom. Use arrows to show how light reflects off the object and into your eyes.

AB Activity 12.4 .4

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Thermal Energy

Watch how heating and cooling matter affect its thermal energy in an animation on the NGScience website.

QuickCode: Z5J9

du ca tio n

Go Online!

Matter is made up of tiny particles that are always in motion. How much these e particles articles move is called thermal energy.

When an object gains thermal mal energy, the particles that make up the e object move faster. fa Its thermal energy increases temperature ases es and its tem also increases.

When an object loses the ses thermal hermal energy, en ene particles that make ake up the object objec obje move slower. Its thermal decreases and its therm mal energy decr d temperature de decreases. ecreases. ease Imagine holdin holding a cup of hot chocolate on a cold day.

How woul would your hands feel?

t When you touch a cup of hot chocolate, energy moves from the cup to your hands m you hands warm up. This movement and your ne of energy that is caused by a difference in te temperature is called heat.

Thermal energy is the energy of the moving particles that make up matter.

1 44

If you place a cool metal spoon into a cup of hot water, heat will flow from the hot water to the cool spoon. The temperature of the spoon will increase. Heat will continue to flow in this direction until the temperature of the water and the spoon are equal.

Think k Deeply

tio n

Heat always flows from a warmer object to a cooler object. It continues to flow between the objects until the temperature of the objects is the same.

How does es the heat hea from the Sun affect on ffect the objects obje changes occur Earth? What ch to the objects?

cooler co

The arrow shows the direction of energy flow within the spoon.

warmer

AB Activity 12.5

1 45

Try This!

In small groups, discuss some daily activities that make use of good conductors of heat and poor conductors of heat.

Create a table to show to other groups.

o passs through roug them Some materials allow heat to more easily than others. Materials allow heat teria als that all to pass through them easily ly are called ca alle ed good conductors of heat. The metal used u ed to t make the pan is a good conductor ctor of of heat. hea at It allows heat to flow easily from m the hotplate hottpla to the food.

Materials that do not heat ot allow he e to pass through them easily are called poor or conductors of heat, or heat insulators. rs. The plastic plas handle on the pan is a poor conductor Heat cannot flow du tor of heat. h through the th he plastic plasstic easily, eas so it does not get as hot as the e metal. metta

al ed

Think Deeply

on

Look at the materials used to make the pan. It has a metal body and a plastic handle.

Why were these materials used? ed?

What makes certain clothes better heat insulators than others? How is this useful?

What ar are some other examples objects that are made from of o good ood or poor conductors of heat?

AB Activities 12.6 – 12.7

1 46

Science Words

Re ga le du ca tio n

Use the words to complete the sentences. vibrations volume pitch natural source of light

1.

artificial source of light reflect ors of h good conductors heat ors of heat poor conductors

An object made by people that gives out light off its own is c called an .

2.

is how loud or soft a sound is.

3.

are rapid back and forth movements.

4.

do not allow heat to o pass through them easily.

5.

We see objects when they

light. lig

6.

allow heat to pass ass through them easily.

7.

is how high or low a sound so is.

8.

g An object in nature that gives out light of its own is a

.

Review

1.

What causes es sounds?

2.

How does es sound travel from its source to our ears?

3.

How sounds? ow can we describe de

4.

Draw aw a Venn Ven diagram to compare natural and artificial sources of light.

1 47

List three ways we use light.

6.

Describe how we are able to see the moon.

Re ga le du ca tio n

5.

7.

Describe how heat moves through the metal rod.

8.

Sophie put a plastic spoon and a metal spoon into a hot cup of water.

Which spoon will feel hotter er when she s touches them?

Explain your answer.

148