Smart Science GRADE 3TEXTBOOK

Philippine Copyright 2009 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the Philippines

Editorial, design, and layout by University Press of First Asia

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ISBN: 978–971–46–0089–8

REVIEWERMarina Balce was a former assistant dean and associate professor at the College of Education, La Salle College–Antipolo. She taught biological sciences for Psychology students and thesis writing for graduating Education students in the same college. She was also a Trainee of the Japan International Cooperation Agency (JICA) at the Aichi University in Nagoya, Japan, where she attended a special training on Practical Work in Elementary School Science. Dr. Balce finished her bachelor’s degree in Secondary Education major in Biology at the University of the East–Manila. She has a master’s degree in Biology Education from the De La Salle University–Manila and a doctorate in Science Education major in Biology from the University of the Philippines–Diliman.

To the LearnerDo you ask yourself questions about the world you live in?

Do you wonder about what lies beyond the blue skies or what rests below the seas? Do you ask questions about the blooming trees and colorful flowers you see, the heat and cold you feel, or the various scents you smell? Do you wonder about the sun, the moon, and the stars? Your young, active mind has so many questions because you are curious about so many things.

This book will help you discover the answers to the questions you have about yourself, the world, and everything beyond it. This book will be your constant companion as you unlock the many mysteries of life through various learning experiences. Moreover, this book will teach you how to apply the wonders of science to your day-to-day activities.

Let this book help you find the answers to the questions you have about yourself, your world, and your universe. Let this take you a step closer to understanding life and in discovering the wonders of science!

Unit 1 You and Your Body

Chapter 1 Your SensesLesson 1 Your Eyes ................................................................................................... 2Lesson 2 How You See Things ................................................................................. 6Lesson 3 Common Eye Disorders and Diseases .........................................................9Lesson 4 Taking Care of Your Eyes ..........................................................................15 Lesson 5 Your Ears ..................................................................................................18Lesson 6 Common Ear Diseases ..............................................................................23Lesson 7 Taking Care of Your Ears ...........................................................................27Lesson 8 Your Nose ................................................................................................31Lesson 9 Common Nose Diseases ...........................................................................35Lesson 10 Taking Care of Your Nose .........................................................................38Lesson 11 Your Tongue .............................................................................................40Lesson 12 Taking Care of Your Tongue .....................................................................44Lesson 13 Your Skin ..................................................................................................46Lesson 14 Common Skin Diseases .............................................................................50Lesson 15 Taking Care of Your Skin ..........................................................................53Think Back ..................................................................................................................55Measure Up! ..................................................................................................................55

Chapter 2 Growing UpLesson 1 Signs of Growing Up ................................................................................57Lesson 2 You Grow Up with Friends .......................................................................62Lesson 3 You Become Smarter as You Grow ...........................................................65Lesson 4 Having a Healthy Body .............................................................................67Lesson 5 Diseases and Your Growth ........................................................................71Lesson 6 Growing Up with Fun ...............................................................................74Lesson 7 Your Environment Affects Your Growth ....................................................78Lesson 8 Good Health Habits ..................................................................................81Think Back ..................................................................................................................84Measure Up! ..................................................................................................................85

Unit 2 Animals and Plants

Chapter 3 Animals in the EnvironmentLesson 1 Animals Move in Different Ways ..............................................................88Lesson 2 Animal Habitat .........................................................................................92

Lesson 3 Kinds of Animals .......................................................................................97Lesson 4 How Animals Get Their Food .................................................................101Lesson 5 Food That Animals Eat ............................................................................105Lesson 6 Animals Have Needs ..............................................................................110Lesson 7 Useful and Harmful Animals ...................................................................114Lesson 8 Taking Care of Animals ...........................................................................118Lesson 9 Safety around Animals ............................................................................122Think Back ................................................................................................................125Measure Up! ................................................................................................................126

Chapter 4 Plants around YouLesson 1 Similarities and Differences among Plants ...............................................128Lesson 2 Where Plants Grow .................................................................................133Lesson 3 Parts of Plants .........................................................................................137Lesson 4 How Plants Grow ...................................................................................141Lesson 5 Importance of Plants ...............................................................................145Think Back ................................................................................................................150Measure Up! ................................................................................................................151

Unit 3 Matter, Energy, Force, and Motion

Chapter 5 Matter around YouLesson 1 Solids ......................................................................................................154Lesson 2 Liquids ....................................................................................................158Lesson 3 Gases ......................................................................................................162Think Back ................................................................................................................164Measure Up! ................................................................................................................165

Chapter 6 Light and SoundLesson 1 Light Travels ...........................................................................................166Lesson 2 Light Bounces .........................................................................................171Lesson 3 Light Bends .............................................................................................173Lesson 4 Colors of White Light ..............................................................................176Lesson 5 How Sound Is Produced .........................................................................179Lesson 6 Loud and Soft Sounds .............................................................................182Lesson 7 Sound Travels .........................................................................................185Think Back ................................................................................................................188Measure Up! ................................................................................................................189

Chapter 7 Force and MotionLesson 1 Making Objects Move .............................................................................191Lesson 2 The Force of a Magnet ............................................................................194Lesson 3 Earth’s Force ...........................................................................................197Lesson 4 Forces of Wind and Water ......................................................................200Think Back ................................................................................................................204Measure Up! ................................................................................................................205

Unit 4 Earth and Sun

Chapter 8 Soil and WaterLesson 1 Your Environment ...................................................................................208Lesson 2 Characteristics of the Soil ........................................................................211Lesson 3 Useful Soil ..............................................................................................215Lesson 4 Soil Pollution ..........................................................................................218Lesson 5 Caring for the Soil ...................................................................................222Lesson 6 Sources of Water .....................................................................................224Lesson 7 Uses of Water .........................................................................................229Lesson 8 Water Pollution .......................................................................................232Lesson 9 Using Water Wisely ................................................................................235Think Back ................................................................................................................237Measure Up! ................................................................................................................238

Chapter 9 The Weather and the SunLesson 1 Air Temperature, Wind, and Air Pressure ................................................240Lesson 2 Humidity, Clouds, and Precipitation .......................................................246Lesson 3 You and the Weather ..............................................................................252Lesson 4 Weather and the Environment .................................................................256Lesson 5 Protection from Harsh Weather Conditions .............................................259Think Back ................................................................................................................263Measure Up! ................................................................................................................264

Bibliograpy ................................................................................................................266

Your body is composed of many parts. Some of these body parts are your sense organs. These include your eyes, ears, nose, tongue, and skin. You can see, hear, smell, taste, and feel because of your senses.

Your body changes as you grow up. As this happens, many things about you also change. You become more interested in the things around you. You want to compare or differentiate things. You start to practice good health habits. You start to make new friends. These things happen because you are growing up.

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Chapter 1

Lesson 1Your Eyes

Your Senses

It is good to observe the things around you.You see the sky in bright hue. And hear the cows that moo! You can smell the flowers in the garden Or taste your favorite food in the kitchenOr feel the cool breeze on the mountain.

You see, hear, smell, taste, and feel. Your sense organs allow you to experience these in real!

1. What is your organ for seeing? 2. What are the parts of your eyes and their functions?

Your eyes are your organs for seeing. You can see different things around you because of your eyes. You can see the different colors of flowers. You can watch the spider spin its web. You can see your friends. You can read books. You can watch your favorite TV program. What other things can you see around you?

3You and Your Body

Each part of the eye has a function. There are parts that protect the eyes. These are the eyelids, the eyelashes, and the eyebrows. They protect the eyes from dust, too much light, and other things that can damage them.

The inside of the eye has other parts. Examine the drawing. It shows a longitudinal section of the eye.

The part of the eye that is shaped like a ball is the eyeball. It is the part that we call the eye. It contains a jellylike substance called the vitreous humor, which gives the eye its round shape.

a. __________________

b. __________________

c. __________________

d. __________________

e. __________________

Longitudinal section of the human eye

aqueous humor

cornea

iris

lens

eye musclevitreous humor

opticnerve

retina

pupil

eyebrow

iris

eyelashes

eyelid

pupil

Parts of the Eye1. Face your seatmate.2. Look at one of his or her eyes.3. Draw its shape. What is its color? _________4. Look at the drawing below. Can you name the parts shown? Choose from the words in the box.

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The eyeball can move in its socket. The muscles that are attached to it let the eye move. Close your eyes and gently touch your eyeballs as they move up and down. What characteristics of the eyeball can you infer by this action?

Do you see the colored part of the eye? It is called the iris. The iris is made up of muscles. At its center is the pupil, an opening that allows light from the outside to enter the eye.

Look at the drawings of the eyes below. Tell the difference between the pupils of each pair of eyes.

In dim light, the pupils of the eyes become larger.

In bright light, the pupils of the eyes become smaller.

The muscles in the iris make the pupil smaller or bigger. In bright light, the iris muscles tighten, making the opening (pupil) smaller. A smaller opening prevents too much light from entering the eye. This way the eye is protected. In dim light, the pupil becomes bigger to let in more light.

Behind the pupil is the lens. Light can pass through it because it is transparent. A tough, transparent material called the cornea covers the lens. Between the lens and the cornea is a watery fluid called the aqueous humor.

At the back part of the eye is a light-sensitive layer called retina. The cells in the retina translate the light that enters the eye into a signal. This signal is then carried to the brain by the optic nerve for processing.

• The eyes are the sense organs for seeing. • Eyelids, eyelashes, and eyebrows protect your eyes from dust, too much

light, and other damaging things.• The inside parts of the eyes are the iris, pupil, lens, cornea, vitreous

humor, aqueous humor, retina, and optic nerve.

5You and Your Body

A. Match the items in Column A with those in Column B. Write only the letter of your answer.

Column A ______ 1. pupil ______ 2. aqueous humor ______ 3. eyeball ______ 4. cornea ______ 5. lens ______ 6. eyelid ______ 7. vitreous humor ______ 8. iris

Column Ba. covers the lensb. an opening that allows light

to enterc. generally referred to as the eye itselfd. colored part of the eyee. gives the eye its round shapef. its transparency allows light to pass through itg. protects the eyes from dirth. watery fluid between the

cornea and the lensi. translates light into signal

B. Make a model of the eye. Use recycled materials to make the model.