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Smart Science Grade 4

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Smart Science 4
    Textbook
Smart Science
GRADE 4
TEXTBOOK


Philippine Copyright 2009 by DIWA LEARNING SYSTEMS INC
All rights reserved. Printed in th...
To the Learner
     Do you ask yourself questions about the world you live in? Do you
wonder about what lies beyond the bl...
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Smart Science Grade 4

  1. 1. Smart Science 4 Textbook
  2. 2. Smart Science GRADE 4 TEXTBOOK Philippine Copyright 2009 by DIWA LEARNING SYSTEMS INC All rights reserved. Printed in the Philippines Editorial, design, and layout by University Press of First Asia No part of this publication may be reproduced or transmitted in any form or by any means electronic or mechanical, including photocopying, recording, or any information storage and retrieval systems, without permission in writing from the copyright owner. Exclusively distributed by DIWA LEARNING SYSTEMS INC 4/F SEDCCO 1 Bldg. 120 Thailand corner Legazpi Streets Legaspi Village, 1229 Makati City, Philippines Tel. No.: (632) 893-8501 * Fax: (632) 817-8700 ISBN 978-971-46-0091-1 REVIEWER Marina E. 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.
  3. 3. To the Learner Do 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 the universe. Let this take you a step closer to understanding life and in discovering the wonders of science!
  4. 4. Unit 1 Human Body Systems: Skeletal, Muscular, and Digestive Chapter 1 The Skeletal System Lesson 1 The Parts of the Skeletal System ......................................................... 2 Lesson 2 Disorders and Diseases of the Skeletal System ................................. 13 Lesson 3 Caring for Your Bones ..................................................................... 19 Think Back ....................................................................................................... 23 Measure Up! ....................................................................................................... 24 Chapter 2 The Muscular System Lesson 1 The Muscles and Their Functions .................................................... 27 Lesson 2 Types of Muscles ............................................................................. 34 Lesson 3 Disorders and Diseases of the Muscular System ............................... 37 Lesson 4 Caring for Your Muscles .................................................................. 41 Think Back ....................................................................................................... 45 Measure Up! ....................................................................................................... 46 Chapter 3 The Digestive System Lesson 1 Inside the Digestive System ............................................................. 49 Lesson 2 Taking in Food through the Mouth .................................................. 54 Lesson 3 Down the Esophagus ....................................................................... 57 Lesson 4 Digestion in the Stomach ................................................................ 59 Lesson 5 Digestion in the Small Intestine ....................................................... 63 Lesson 6 Digestion in the Large Intestine ....................................................... 66 Lesson 7 Diseases and Disorders of the Digestive System .............................. 70 Lesson 8 Caring for Your Digestive System .................................................... 76 Think Back ....................................................................................................... 79 Measure Up! ....................................................................................................... 80 Unit 2 The World of Animals and Plants Chapter 4 The World of Animals Lesson 1 Animal Reproduction ...................................................................... 86 Lesson 2 Baby Animals .................................................................................. 91 Lesson 3 Life Cycles ....................................................................................... 95 Lesson 4 Complete Metamorphosis ................................................................ 99
  5. 5. Lesson 5 Incomplete Metamorphosis ........................................................... 103 Lesson 6 Beneficial and Harmful Animals .................................................... 106 Lesson 7 Protection from Harmful Animals .................................................. 112 Lesson 8 Endangered Animals ...................................................................... 116 Think Back ..................................................................................................... 119 Measure Up! ..................................................................................................... 120 Chapter 5 The World of Plants Lesson 1 The Flower and Its Parts ................................................................ 122 Lesson 2 How Do Plants Reproduce? ........................................................... 129 Lesson 3 Fertilization in Flowers .................................................................. 132 Lesson 4 Seed: Parts and Functions .............................................................. 135 Lesson 5 Seed Germination ......................................................................... 138 Lesson 6 Spreading Seeds ............................................................................ 141 Lesson 7 Plants Also Reproduce Asexually ................................................... 144 Lesson 8 Conserving Plants .......................................................................... 149 Think Back ..................................................................................................... 152 Measure Up! ..................................................................................................... 153 Unit 3 Matter, Energy, and Force Chapter 6 Matter All around Us Lesson 1 What Is Matter? ............................................................................. 156 Lesson 2 Properties of Matter ....................................................................... 160 Lesson 3 What Are Mixtures? ....................................................................... 166 Think Back ..................................................................................................... 169 Measure Up! ..................................................................................................... 170 Chapter 7 Energy and Force Lesson 1 Heat It Up! .................................................................................... 172 Lesson 2 How Heat Is Transferred ................................................................ 177 Lesson 3 Safety First ..................................................................................... 183 Lesson 4 Friction .......................................................................................... 187 Lesson 5 Controlling Friction ....................................................................... 190 Think Back ..................................................................................................... 194 Measure Up! ..................................................................................................... 194
  6. 6. Unit 4 The Changing Earth, Weather, and Beyond Chapter 8 The Changing Earth Lesson 1 Water as an Agent of Change ........................................................ 198 Lesson 2 Temperature and Rocks ................................................................. 202 Lesson 3 Wind and Soil Erosion ................................................................... 204 Lesson 4 Plants and Animals Break Rocks .................................................... 208 Lesson 5 People Can Also Break Rocks ........................................................ 211 Lesson 6 Ways to Prevent Soil Erosion ......................................................... 214 Think Back ..................................................................................................... 218 Measure Up! ..................................................................................................... 219 Chapter 9 Weather Elements Lesson 1 Different Weather Elements ........................................................... 221 Lesson 2 Observing Changes in Air Temperature ......................................... 224 Lesson 3 Observing Changes in Wind Speed and Direction ......................... 228 Lesson 4 Observing Cloud Formations ......................................................... 233 Think Back ..................................................................................................... 237 Measure Up! ..................................................................................................... 238 Chapter 10 The Sun-Moon-Earth System Lesson 1 The Moving Earth .......................................................................... 240 Lesson 2 Earth Revolves around the Sun ...................................................... 243 Lesson 3 The Moon in Motion ..................................................................... 246 Lesson 4 Moon Phases ................................................................................. 249 Lesson 5 Eclipses ......................................................................................... 252 Lesson 6 Tides ............................................................................................. 257 Think Back ..................................................................................................... 261 Measure Up! ..................................................................................................... 262 Bibliography ............................................................................................................. 265
  7. 7. Unit 1 Human Body Systems: Skeletal, Muscular, and Digestive Your body is composed of parts that work together to keep you alive. These parts perform their specific functions so efficiently that you hardly notice them working at all! Activities that are as simple as the movement of your finger or as complex as the digestion of the food that you have eaten are results of the important functions of your body systems. In this unit, learn about three body systems, namely, skeletal, muscular, and digestive. Know which diseases can affect them and how to take good care of them.
  8. 8. Chapter 1 The Skeletal System Have you seen a building undergoing construction? What have you observed? As you may have noticed, constructing a building starts by putting together a system of beams and girders, or what is called a framework. The framework is held together by special bolts to make it strong. It must be strong because it provides support to the floors and walls of the building. This way, the building does not collapse. The human body is just like a building. It has a framework called the skeleton which is made up of superbly joined and balanced system of bones held by ligaments, tendons, and joints. Lesson 1 The Parts of the Skeletal System Find Out 1. What are the functions of the skeletal system? 2. What are the parts of the skeletal system? What are the functions of each part? 3. How are the bones in the human body classified? 4. What are cartilage, joint, and ligament? Your skeleton gives your body support, shape, and protection. It is made up of bones that have different shapes, sizes, and functions. 2 Smart Science 4
  9. 9. The Bones As a newborn, you may have as many as 350 bones. Soon after birth, your bones start to harden and some of them fuse together. This is due to the accumulation of materials such as calcium and phosphorus in the bones. This process is called ossification. As bones fuse together, they form fewer but bigger and stronger bones. The hardening of the bones continues until early adulthood. An adult’s skeletal system consists of 206 bones. skull clavicle sternum ribs humerus vertebral column radius ulna pelvic girdle bones of the hand femur patella tibia fibula bones of the foot An adult’s skeletal system The bones of the body are grouped into two: the axial and perpendicular skeletons. The axial skeleton consists of the skull, the backbone, and the rib cage. The axial skeleton is made up of 80 bones. Human Body Systems: Skeletal, Muscular, and Digestive 3
  10. 10. The skull protects the brain. It consists of 22 different bones—eight paired bones and six unpaired bones. The bones of the skull are divided into the cranial bones and the facial bones. The cranial bones hold and protect the brain. The facial bones, which are found below the skull, provide the framework that forms the face. Facial Bones Cranial Bones ethmoid bone frontal bone lacrimal bone parietal bone nasal bone sphenoid bone zygomatic bone temporal bone maxilla lacrimal bone mandible occipital bone Bones of the skull Get a partner and run your fingers down the middle of his or her back. Describe the body part that you feel. The backbone is a chain of bones that runs down the middle of your back. It is also called the spine or vertebral column. There are 26 vertebrae (or bones of the spine) attached together by joints. The backbone protects the thick cord of nerves called the spinal cord. The backbone 4 Smart Science 4
  11. 11. The bones at the sides of your chest form the rib cage. The rib cage protects the heart, lungs, and other internal organs. It also helps you breathe. It consists of 12 pairs of flat, curved bones called ribs. They are connected to each other by muscles. The first upper ribs, called the true ribs, curve around from the spine and join the breast bone in front. The next three pairs are called the false ribs. Each false rib is connected to the rib above it. The lowest two pairs of ribs, called the floating ribs, are attached only to the backbone. sternum true ribs false ribs floating ribs The rib cage Place your hand against your chest. The flat bone that you can feel in front of your chest is the sternum or breast bone. It is connected to the ribs by cartilage. Breathe deeply three times. Does your chest expand each time you inhale? The cartilage that connects the sternum to the ribs can stretch, allowing you to breathe deeply. Human Body Systems: Skeletal, Muscular, and Digestive 5
  12. 12. The appendicular skeleton is made up of the bones of the girdles and appendages. The appendages include the arms, hands, legs, and feet. There are two girdles in the human body—the pectoral girdle and pelvic girdle. The appendicular skeleton is made up of 126 bones. Pectoral girdle Pelvic girdle The pectoral girdle allows you to move your arms and anchors them in your skeleton. The pelvic girdle connects your lower extremities to the axial skeleton and supports your abdominal organs. Your hands are the most nimble parts of your body. You use them to hold heavy objects, but they are also suited to perform delicate tasks like threading a needle. The bones of your feet bear the entire weight of your body. When you stand, walk, or jump, your feet give you support and balance. 6 Smart Science 4
  13. 13. Have you wondered how your bones are distributed in your body? The table below shows the distribution of bones in the human body. The Bones of the Body Types of Skeleton Number of Bones Axial Skeleton 80 bones backbone 26 ribs 24 (12 on each side) skull 22 ears 6 (3 each) throat 1 sternum 1 Appendicular Skeleton 126 bones hands 56 (28 each) feet 52 (26 each) legs 6 (3 each) arms 6 (3 each) shoulders 4 hips 2 Total 206 bones The Parts of the Bone The outer layer of the bone is called the compact bone spongy compact bone. This bone layer is dense and looks smooth. It forms spongy bone (spaces contain the protective outer red bone marrow) part of all bones. The compact bone compact bone helps yellow bone withstand bumps and blood vessel central cavity blood vessels and bangs that your bones (contains yellow nerve in central canal may encounter. It also bone marrow) consists of minerals The bone structure such as phosphorus and calcium. Human Body Systems: Skeletal, Muscular, and Digestive 7
  14. 14. Inside the compact bone is the spongy bone, which is very porous. The spaces in the spongy bone are filled with blood and soft tissue, called red marrow. The red marrow produces red blood cells, some white blood cells, and platelets. It also repairs the compact bone. Calcium and phosphorus are the minerals needed to build strong bones. What do you think will happen if bones do not have these minerals? The experiment below will help you find out what happens when bones lose their mineral content. Explore Removing Minerals from the Bones You need: three chicken bones (same part/size), three small jars, vinegar, water, gloves Do the following: 1. Clean the chicken bones thoroughly. Try to bend each bone carefully. Can you bend them? __________________________________________ 2. Half-fill one jar with water and the other with vinegar. Leave the third one empty. 3. Put one chicken bone into each jar. Label the setups as follows: “Bone in Water,” “Bone in Vinegar,” and “Bone in Jar.” 4. Leave the jars in a safe place for two days. 5. After two days, remove the chicken bones from the jars and carefully wash them with water. Air dry the bones and then try to bend them. Compare the texture of the three bones. a. Which bone(s) can be bent? ________________________________ b. Which bone(s) cannot be bent? _____________________________ c. What did the vinegar do to the chicken bone? _________________ 8 Smart Science 4
  15. 15. If calcium and phosphorus are removed, bones lose their hardness and strength. This is why it is important for you to eat food rich in these minerals to keep your bones strong and healthy. Dairy products such as milk and cheese are rich in calcium. Vitamin D also keeps your bones strong because it helps your body absorb calcium. Cartilage, Joints, and Ligaments When you were born, most of your bones were not yet fully developed. They were made up mostly of cartilage. Cartilage is a tough, semi transparent, elastic tissue. Almost all bones develop from cartilages. Cartilage has several functions. It covers the surface of joints, allowing bones to slide over one another, reducing friction and preventing damage. The cartilage also acts as a shock absorber. bone cartilage bone Cross-section of a joint Feel your elbow and your knee. You can flex and extend your arm because of your elbow. You can perform the same movements with your legs. This is all because of your joints. A joint is a point where two bones meet. Joints allow your body to move in many ways. Joints are classified by their range of movement. Immovable joints, called fibrous joints, do not move. The dome of the skull, for example, is made of bony plates, which must be immovable to protect the brain. Between the edges of these plates are links or joints of fibrous tissue. Fibrous joints also hold the teeth in the jawbone. Human Body Systems: Skeletal, Muscular, and Digestive 9
  16. 16. nasal bone Partially movable joints or cartilaginous joints move a little. cartilage They are linked by a cartilage. Examples of cartilaginous joints are those in the windpipe or trachea, bridge of the nose, and ears. Freely movable joints or synovial Bone cartilage of the nose joints move in many directions. The main joints of the body—found at the hips, shoulders, elbows, knees, wrists, and ankles—are freely movable. They are filled with synovial fluid, which acts as a lubricant to help the joints move easily. According to their movements, synovial joints may be classified as the following: 1. Gliding joints – These joints permit side-to-side and back-and-forth movements. An example is the wrist joint. 2. Hinge joints – These joints allow only back-and- forth movements such as bending and straightening. Examples are elbow joints and knee joints. 3. Pivot joints – These joints allow rotational movement pivot joint only. An example is the hinge joint joint between the bones in the forearms. 4. Ball-and-socket joints – These joints permit side- gliding joint to-side, back-and-forth, and rotational movements. ball-and-socket joint Examples are shoulder and hip joints. The synovial joints 10 Smart Science 4
  17. 17. The bones in synovial joints ligamentum flavum are held together by ligaments. intertransverse A ligament is a tough band of facet ligament capsulary white, slightly elastic tissue. ligament It binds the bones together to posterior longitudinal prevent dislocation. Ligaments interspinous ligament ligament also support some internal anterior organs like the bladder and supraspinous longitudinal liver. ligament ligament Knowing the parts of your Ligament skeletal system will make you understand better how to take good care of it. Home Economics Bulalo, a Filipino dish that originated from Batangas, is a very tasty soup whose main ingredient is the kneecap of a cow. Contrary to popular belief that one eats the brain of the cow in bulalo, what you actually find inside the kneecap is the marrow—a kind of soft tissue that is responsible for the storage of fats. Keep in Mind • The skeletal system is the framework of the human body. It is made up of bones that give support, shape, and protection to the body. • The skeletal system is divided into two groups: axial and appendicular skeletons. • The axial skeleton consists of the skull, the backbone, and the rib cage. The appendicular skeleton consists of the bones of the appendages (arms, hands, legs, feet) and the girdles (pectoral and pelvic). • The outer layer of the bone is called the compact bone. It forms the protective outer part of all bones. Human Body Systems: Skeletal, Muscular, and Digestive 11
  18. 18. • The inner layer of the bone is called the spongy bone. The spaces between the spongy bone are filled with blood and red marrow. • Cartilage is a tough, semi transparent, elastic tissue that covers the surface of joints. A joint is a point where two bones meet. • Joints allow your body to move in many ways. Joints can be freely movable, partially movable, or immovable. • A ligament is a tough band of white, slightly elastic tissue that binds the bone together to prevent dislocation. Challenge Yourself Write T on the blank space if the statement is true. If it is false, change the underlined word or phrase to make the statement true. __________ 1. The skeleton is the framework that supports and protects the body. __________ 2. The bones of the legs are part of the axial skeleton. __________ 3. The bones of the feet support the weight of the entire body. __________ 4. An adult person has 206 bones. Of these, 22 bones form the rib cage. __________ 5. The rib cage protects the heart and the lungs. __________ 6. The yellow marrow repairs the hard layer of the bone. __________ 7. Vitamin C helps the bone absorb calcium. __________ 8. Hinge joints permit side-to-side, back-and-forth, and rotational movements. __________ 9. Like the immovable joint, the knee joint can be bent or straightened. __________10. Pivot joints allow rotational movement only. 12 Smart Science 4

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