Mastering the Grade 4

Transcription

1 Mastering the Grade 4 Science TeKS Mark Jarrett Ph.D., Stanford University Stuart Zimmer James Killoran Jarrett Publishing Company East Coast Office southern Office West Coast Office P.O. Box Nettles Boulevard 10 Folin Lane Ronkonkoma, NY Jensen Beach, FL Lafayette, CA Fax:

2 TABLE OF CONTENTS x Grade 4 Science TEKS v vi INTRODUCTION 1 y Lesson 1: How to Answer Multiple-Choice Questions UNIT 1: THE NATURE OF SCIENCE 13 y Lesson 2: What Is Science? y Lesson 3: Scientific Reasoning y Lesson 4: The Growth of Scientific Knowledge x Review for Unit 1: The Nature of Science UNIT 2: SCIENTIFIC INVESTIGATION 62 y Lesson 5: Types of Scientific Investigation y Lesson 6: Designing a Scientific Investigation y Lesson 7: Conducting a Scientific Investigation y Lesson 8: Analyzing the Results of a Scientific Investigation x Review for Unit 2: Scientific Investigation UNIT 3: MATTER, FORCE, AND ENERGY 128 y Lesson 9: Matter y Lesson 10: Force and Motion y Lesson 11: Energy x Review for Unit 3: Matter, Force, and Energy UNIT 4: EARTH AND SPACE 176 y Lesson 12: Earth s Changing Surface y Lesson 13: Earth s Resources y Lesson 14: Weather y Lesson 15: Space x Review for Unit 4: Earth and Space UNIT 5: ORGANISMS AND ENVIRONMENTS 235 y Lesson 16: Organisms y Lesson 17: Ecosystems y Lesson 18: Heredity x Review for Unit 4: Organisms and Environments UNIT 6: PRACTICE TEST 282 y Lesson 19: Grade 4 Practice Science Test x Glossary iv

3 LESSON 1: How to Answer Multiple-Choice Questions As you can see, this question tests your ability to recall information about different types of forces. UNLOCKING THE ANSWER What do you think is the best answer to Question 1? Explain why you selected that answer. USING THE E-R-A APPROACH Whatever type of science question you are asked, we suggest you follow the same three-step approach to find the answer. Think of this as the E-R-A approach: Examine The Question Recall What You Know Apply What You Know Let s look at each of these steps to see how they help you find the correct answer. STEP 1: EXAMINE THE QUESTION Start by reading the question carefully. Be sure you understand any information the question provides. Then make sure you understand exactly what the question is asking for. The question on page 2 asks you to name the force that pulls objects towards Earth.

4 Mastering the Grade 4 Science TeKS STEP 2: RECALL WHAT YOU KNOW Next, you need to identify the science topic that the question asks about. Take a moment to think about what you know about that topic. Mentally review the important concepts, facts, and relationships you can remember. You should think about what you can recall from your study of forces. The question asks which force pulls things to Earth. Sit back and think about what you can recall about this topic. Remember that gravity is the name that scientists have given to the force of attraction between all objects. Gravity is the force that keeps the Earth in orbit around the sun. Gravity also causes objects to fall to Earth s surface. STEP 3: APPLY WHAT YOU KNOW Now take what you can recall and apply it to the question. Often, it helps to mentally answer the question before you look at the choices. Then see if any of the answer choices is what you think the answer should be. Look at all the answer choices carefully to make sure you choose the best one. Cross out any obviously wrong choices. 1 Which force pulls objects towards the Earth? A gravity B friction C magnetism D electricity Here, the question asks you to identify which force pulls objects towards Earth. To answer this question, you need to recall the characteristics of different types of forces. Then apply this information to select the force that pulls objects to Earth. RELATING OR EXPLAINING SCIENTIFIC FACTS Some science questions may ask you to relate or explain scientific facts. These science questions go beyond just recalling information. They ask you to use your higher-level thinking skills. These questions might ask you to:

5 LESSON 1: How to Answer Multiple-Choice Questions Compare things Explain why something happened Give an example Identify a cause or effect Place events or steps in order Let s look at a sample question asking you to explain why something happens: 2 Why does the moon appear to change its shape? A Our view of the sun-lit part of the moon changes. B Earth s orbit around the sun changes. C The sun s temperatures increase and decrease. D Earth s spinning reflects light on the moon. UNLOCKING THE ANSWER What do you think is the best answer to Question 2? To answer this type of question, let s again apply the E-R-A approach. Step 1: Examine the Question Read the question carefully and be sure you know what it asks for. UNLOCKING THE ANSWER What informaion does the question give you? What does the question ask?

6 Lesson 7 CONDUCTING A SCIENTIFIC INVESTIGATION TEKS COVERED IN LESSON 7 A4.3 Planning classroom and outdoor investigations. A4.4 Investigations of the natural world. B4.1B Scientists conserve and recycle materials. B4.2 Inquiry during laboratory and outdoor investigations. B4.4 Use of various tools and materials for scientific inquiry. B4.4A Collect, record, and analyze information using tools. In Lessons 5 and 6, you learned how scientists design experiments to test hypotheses and answer scientific questions. In this lesson, you will learn how scientists actually conduct experiments by making observations, taking measurements, and recording their findings. Important Ideas A. Scientists use their senses to make observations. Tools like microscopes and hand lens often improve their observations. B. Scientists often use special instruments to take measurements. y Distance: Scientists use metric rulers. y Mass: Scientists use balances. y Weight: Scientists use spring scales. y Volume: Scientists use graduated cylinders. y Temperature: Scientists use thermometers. C. Scientists use metric units (S.I.) of measurement. D. Scientists observe change by recording the passage of time along with other measurements. 92

7 LESSON 7: Conducting a Scientific Investigation 93 Key Terms in this Lesson X Metric System X Gram / Kilogram X Double-Pan Balance X Meter / Centimeter X Volume X Triple-Beam Balance X Mass X Liter / Milliliter X Record Keeping To conduct an experiment, scientists usually bring their materials and instruments together in a specific order. They record each step as they proceed so that other scientists can repeat the same investigation. Later scientists may come up with different results if they do not repeat this same order. Finally, scientists try to choose materials and instruments that can be conserved, reused, or recycled. PROCEDURE For example, to study the effect of sunlight on lima bean plants, a scientist might take the following steps: STEP 1: Assemble the Materials The scientist puts four lima bean plants in four flower pots filled with soil. Each plant is the same height and each pot is the same size. All four pots have the same type of soil and will receive the same amount of water. STEP 2: Record the Heights of the Plants The scientist measures the exact height of each plant with a metric ruler. The scientist then records their heights in centimeters (cm). STEP 3: Place the Plants in Various Locations The scientist places the four plants in one room. One plant is placed on a shelf in a shady part of the room without receiving any direct sunlight.

8 94 Mastering the Grade 4 Science TeKS The second plant is placed on a window sill in direct sunlight for only two hours each day. The scientist uses a stopwatch or alarm clock to record the time. The third plant is placed on the same window sill in direct sunlight for four hours each day. The last plant is placed on the same window sill in direct sunlight for exactly six hours. 2:00 4:00 6:00 No Direct Sunlight 2 Hours of Sunlight 4 Hours of Sunlight 6 Hours of Sunlight STEP 4: Observe and Record the Information Each week for four weeks, the scientist measures the exact heights of each plant with a metric ruler and records the results in a table. Height at the Start Height after 1st Week Height after 2nd Week Height after 3rd Week Height after 4th Week Plant 1 Plant 2 Plant 3 Plant 4 No Direct Sunlight 2 Hours of Sunlight 4 Hours of Sunlight 6 Hours of Sunlight OBSERVATIONS As you can see, observing and measuring are very important in scientific investigation. In many investigations, scientists simply observe what happens. They use one or more of their senses to tell what is happening.

9 LESSON 7: Conducting a Scientific Investigation 103 Complete the graphic organizer below by identifying the tools used by scientists for measurement. For each tool, state what it is used to measure. Then identify one or more units of measurement the tool often uses. For example, a thermometer measures temperature in degrees Celsius ( C). Metric Ruler Learning with Graphic Organizers Graduated Cylinder Beaker Units of Measurement: Units of Measurement: Units of Measurement: Double-Pan Balance Triple-Beam Balance Scientific measurement Units of Measurement: Units of Measurement: Spring Scale Thermometer Stop Watch Units of Measurement: Units of Measurement: Units of Measurement:

10 Lesson 8 ANALYZING THE RESULTS OF A SCIENTIFIC INVESTIGATION TEKS COVERED IN LESSON 8 B4.2C Construct tables, charts, bar graphs, and maps. B4.2D Analyze data and interpret their patterns. B4.2E Perform repeated investigations to increase reliability. B4.2F Communicate valid, written results supported by data. In earlier lessons of this unit, you learned how scientists design and conduct scientific investigations. In this lesson, you will learn how scientists analyze their results. To analyze something, you look at it closely to understand it better. Scientists interpret patterns, draw conclusions, and communicate their findings to others. Important Ideas A. Scientists often organize their results into tables, bar graphs, charts, diagrams, or maps. These ways of organizing information often reveal patterns. B. Scientists analyze data and interpret patterns to provide reasonable explanations of natural events. C. Scientists repeat their investigations to increase the reliability of results. D. Scientists draw conclusions and make predictions based on their results. E. Scientists communicate their results and conclusions to others. Key Terms in this Lesson X Table X Diagram X Generalization X Bar Graph X Map X Reliability X Chart X Conclusion X Communicating Results 107

11 LESSON 8: Analyzing the Results of a Scientific Investigation 109 Applying What You Have Learned y Based on the table, how much did Plant 2 grow in the second week? y How much did the plant that received 6 hours of direct sunlight each day grow in the third week? y Which plant grew the most in the 4 weeks? y Which plant grew the least in the 4 weeks? y What patterns can you see in this data? BAR GRAPHS A bar graph is made up of bars of different lengths. Each bar represents a quantity of something. Each bar is labeled or a key is provided to tell what each bar represents. Carefully examine the bar graph below. Total Growth (in cm) LIMA BEAN PLANT GROWTH Plant 2 (23) Plant 3 (38) Plant 4 (62) Plant 1 (10) Hours of Direct Sunlight Each Day This graph shows the total growth, in centimeters, of each of the four lima bean plants. The numbers on this bar graph are based on the growth of the plants shown on the table on the previous page.

12 150 Mastering the Grade 4 Science TeKS Applying What You Have Learned Which creates more friction: skaters on an ice skating rink or a piece of sandpaper rubbing against a piece of wood? Explain your answer. ACTING AS AN AMATEUR SCIENTIST y You can design your own experiment to test the effect of different kinds of force on objects. For example, you might want to test the effect of gravity on objects of different sizes. Type of Force Tested: Gravity Well-Defined Question: Do balls of different masses fall at different speeds? Hypothesis: A ball with a larger mass will roll down a ramp faster than a ball with a smaller mass. Variable: The mass of the ball. Equipment / Materials: Two balls of different sizes, such as a marble and a baseball; a wooden ramp of at least 1 m in length; a triple-beam balance; a timing device. continued

13 LESSON 10: Force and Motion 151 Plan / Steps for Conducting the Experiment: 1. Using the triple-beam balance, measure the mass of each ball. 2. Let each ball roll down the ramp. 3. Time how long it takes each ball to reach the end of the ramp. 4. Repeat the experiment several times to increase the reliability of your results. Observations / Measurements / Results: Record your results in the following table: Larger Ball Smaller Ball Trial 1 Seconds Seconds Trial 2 Seconds Seconds Trial 3 Seconds Seconds Trial 4 Seconds Seconds Average Time / Reflection Seconds Seconds Conclusions / Reflections: What conclusions can you draw? Do your results support or disprove the hypothesis (see page 150)? y Now design an experiment of your own. The experiment should test the effect of any kind of force on an object. Use the same steps outlined in the experiment above. Begin with a well-defined question. Well-Defined Question: Hypothesis: continued

14 Lesson 11 Energy TEKS COVERED IN LESSON 11 B4.6 Energy exists in many forms. B4.6A Forms of energy include mechanical energy, sound energy, heat / thermal energy, light, and electricity. B4.6B Conductors and insulators. B4.6C Electricity travels in a closed path, known as a circuit, and creates electromagnetism. Where does force come from? Force is actually powered by energy. In this chapter, you will learn about different kinds of energy. A. Energy is an ability to do work. Important Ideas B. There are different kinds of energy. These include mechanical energy, sound energy, heat / thermal energy, light and electricity. C. Conductors carry energy easily; insulators block the flow of energy. D. Electricity travels in a closed path, known as a circuit. When electricity flows, it creates an electromagnetic field. Key Terms in this Lesson X Mechanical Energy X Electricity X Electromagnetic Field X Sound Energy X Light X Conductor X Heat / Thermal Energy X Electric Circuit X Insulator FORMS OF ENERGY Energy is harder to think about than matter. You cannot always see energy, but you can sometimes feel it. Some days you may feel more energetic than others. You feel like doing things. 157

15 158 Mastering the Grade 4 Science TeKS Think of energy as the power to do things. Scientists define energy as an ability to do work. Energy can cause movement or changes in matter. There are many kinds of energy. These include: Mechanical Energy Sound Energy Heat / Thermal Energy Light Electricity Let s take a closer look at each of these forms of energy. MECHANICAL ENERGY Mechanical energy is the energy that makes things move. It is the energy behind force. For example, a ball falling down a hill is using mechanical energy. When you roll a ball up a hill, you are actually storing mechanical energy. This windmill captures the wind s mechanical energy. SOUND ENERGY Sound is another form of energy. This form of energy is carried along waves of air. For example, when a person pulls a guitar string, the string begins to vibrate. The energy from the vibrating string causes the air to vibrate. Our ears are sensitive to these vibrations. The energy from these vibrations passes to our ears, and we hear these vibrations as sound. Vibrating air Force is applied to the string to make it vibrate Our ears hear these vibrations as sounds

16 LESSON 11: Energy 161 Applying What You Have Learned Identify two ways that you have used electricity today Learning with Graphic Organizers Complete the graphic organizer below by identifying each of the following forms of energy. Then give one example for each. Mechanical Energy Sound Energy Heat / Thermal Energy Forms OF of Energy ENergy Light Energy Electrical Energy

17 162 Mastering the Grade 4 Science TeKS SPECIAL CHARACTERISTICS OF ELECTRICITY Electrical energy has several important special characteristics. These characteristics make electricity a very useful form of energy. ELECTRIC CIRCUITS Electricity flows in a closed path, known as a circuit. A simple electrical circuit is a system with three parts: A source that provides electricity Something that uses electricity Wires to carry the electricity A battery is one source that produces electricity. Every battery has a positive (+) and a negative ( ) side. Wires connected to the battery carry the electricity. Electricity will only move if the wires and other parts form a complete circuit. This provides a closed and continuous path for the electricity to move through. For example, imagine a simple circuit with a light bulb at one end and a battery at the other (Figure 1). Electricity leaves the negative side of the battery and moves through the wire to the light bulb. The electricity then moves through the light bulb and causes the bulb to light up. The electricity next continues moving through the wires to the positive side of the battery. The flow of electricity is continuous. + Figure 1 + If this circuit is cut at any point, the electricity moving around the circuit will stop (Figure 2). As a result, the light bulb will have no electricity flowing through it. The bulb will go out. + Figure 2 +

18 The wires must also be connected to each side of the battery. If both ends of the wire are connected to the same side of the battery, the electricity will not move around the circuit (Figure 3). The bulb will receive no energy and will not light. LESSON 11: Energy If both ends of the wire are connected to the same side of the light bulb, the electricity will go around the circuit without ever going through the light bulb (Figure 4). Again, the bulb will not light up. In fact, for any electric appliance to work, there must be a complete path from the power source to the appliance, through its parts, and back to the power source. This is true for a toaster as well as for a light bulb. Applying What You Have Learned + Figure 3 Figure 4 + Each circuit below has light bulbs, a battery as a source of power, and wires y In which circuit will the lights bulbs go on? y Why won t the other circuits light the bulbs? When electricity runs through some materials, it makes them hot. People use this characteristic of electricity to make useful appliances. For example, irons, toasters, and electric heaters all produce heat when electricity runs through them. A few materials become so hot with electricity that they glow. Inside a light bulb is a tiny wire, known as a filament, that glows from this heat. Special gases in the light bulb make this glow even brighter, producing light energy.

19 LESSON 11: Energy 165 Learning with Graphic Organizers Complete the graphic organizer below by describing some of the special characteristics of electricity. Electric Circuits Electromagnetism Characteristics Of Electricity CONDUCTORS AND INSULATORS Some materials are especially good at carrying different types of energy. These materials are called conductors. They conduct energy from one place to another. For example, copper is a very good conductor of electricity. That is why electric wires are often made of copper. Other materials are good conductors of sound, heat, or light energy. Insulators. Other materials do not carry some forms of energy very well. These are called insulators. Insulators can be used to block the movement of energy. Rubber and plastic are two materials that are not good conductors of electricity. For this reason, Copper wire Insulation Electricity runs through only the copper wire these materials are often used to insulate electrical wires. We cover wires with these insulators so that we can handle them without getting a shock from the electricity. Other insulators might be used to block sound or heat. For example, a builder may use rubber or other materials for sound proofing to reduce noise.

20 REVIEW FOR UNIT 3: Matter, Force, and Energy 171 CONCEPT MAP FOR MATTER, FORCE, AND ENERGY Fixed Volume; Shape Fits Container MASS Fixed Volume and Shape LIQUID VOLUME MAGNETISM SOLID STATES OF MATTER SIZE MEASURABLE PROPERTIES OF MATTER TEMPERATURE MAGNETISM DOES IT FLOAT? CAUSES MATTER TO START MOVING OR CHANGE ITS MOTION TYPES OF FORCE PUSH-AND-PULL GAS No Fixed Volume or Shape; Fills Container MATTER ANYTHING THAT HAS MASS AND VOLUME FORCE GRAVITY MIXTURES FRICTION One Substance Is Evenly Spread in Another SOLUTIONS Only Some Substances Dissolve in Others MATTER, FORCE, AND ENERGY Energy of Movement MECHANICAL ENERGY ENERGY AN ABILITY TO DO WORK Energy Carried Through Air in Waves Particles of Energy Can Travel Through Space SOUND ENERGY LIGHT FORMS OF ENERGY HEAT/THERMAL Energy Created by Motion of Tiny Particles in Matter ELECTRICAL Electrical Circuits Electricity Moves in a Closed Path Electro- Magnetism Electricity Creates an Electromagnetic Field

21 Lesson 18 Life Cycles and Heredity TEKS COVERED IN LESSON 18 B4.10 Organisms undergo life processes and have structures that help them to survive in their environment. B4.10B Many likenesses between parents and offspring are inherited, such as eye color in humans or the shapes of leaves in plants. Other likenesses are learned, such as table manners. B4.10C Explore, illustrate, and compare life cycles of living organisms such as butterflies, beetles, radishes, and lima beans. In this lesson, you will learn about the life cycles of plants and animals. You will also look at how many organisms resemble their parents because of inherited traits or learned characteristics. Important Ideas A. Living organisms go through stages known as life cycles. They begin life, grow, reproduce, become older, and die. B. Many organisms change their form as they go through their life cycle. For example, insects are born from eggs. Many insects come out of their eggs as worm-like larvae. Later, they change their form to become adults with wings. C. Plants also go through life cycles. They begin as a seed. The seed germinates. Later, it grows small leaves and becomes a seedling. Finally, the seedling continues to grow into a mature plant. Many plants grow flowers. The flowers make seeds, and the plant life cycle begins again. D. Many characteristics, like eye color or the shape of a leaf, are inherited from parents. E. Humans and other animals learn some behaviors. 262

22 LESSON 18: Life Cycles and Heredity 263 Key Terms in this Lesson X Life Cycle X Pupa X Likeness X Metamorphosis X Germinate X Heredity X Photosynthesis X Seedling X Learned Behavior LIFE CYCLES Do you look the same as you did when you were a baby? Or the same as your parents look now? Of course not! As you get older, you go through changes. Most living organisms change as they get older. They pass through changes known as life cycles. THE LIFE CYCLES OF ANIMALS Every type of animal has its own unique life cycle. For example, insects, fish and birds are born from eggs. The babies of mammals are born live from their mother. Most animals then grow bigger. When they reach adulthood, they reproduce (have their own children). They continue to age and eventually die. Some animals just grow larger as they move from childhood to adulthood. Other animals completely change their form. For example, many insects go through a special process called metamorphosis. In this process, the insect changes its form. The Life Cycle of a Butterfly Butterflies, like other insects, lay eggs. Some butterflies are very selective about where they lay their eggs. Out of each egg comes a worm-like larva. We call a butterfly larva a Egg Larva (Caterpillar) Pupa (Chrysalis) Adult Butterfly caterpillar. Caterpillars eat leaves as they grow. The larva then develops a hard case known as pupa (or chrysalis). (Some moths wrap their pupa in silk threads, known as a cocoon.) Inside the pupa, it forms wings and other adult parts. After a period of time, an adult butterfly with beautiful wings comes out of the pupa. To remember these stages, think of the letters E-L-P-A: egg-larva-pupa-adult.

23 264 Mastering the Grade 4 Science TeKS The Life Cycle of a Beetle A beetle has a life cycle similar to that of a butterfly. Much of its life is spent underground. A female adult beetle lays hundreds of tiny, oval eggs. One beetle larva, or grub, comes out of each egg. It looks like a worm with segmented skin and legs. The grub has a powerful chewing mouth. LIFE CYCLE OF THE BARK BEETLE Eggs Each grub eats large amounts of leaves or grass as it grows. As the grub grows it sheds its Pupa skin and forms a new skin several times. The larva then changes into a pupa. Out of the pupa comes an adult, with legs, antennae, and wings, completing metamorphosis. Female beetles mate and lay eggs, starting the cycle all over again. ACTING AS AN AMATEUR SCIENTIST Larva Illustrate and describe each stage in the life cycle of a beetle. Your teacher may have beetles in your classroom for you to observe their life cycle changes. In this case, create your drawing from your own observations. Egg Adult Stage Your Drawing Your Word Description Larva (Grub) Pupa Adulthood

24 LESSON 18: Life Cycles and Heredity 265 y How do the life cycles of butterflies and beetles compare? Think about how they are similar and how they are different: Similarities: Applying What You Have Learned Differences: y How does the metamorphosis of insects differ from the human life cycle? THE LIFE CYCLE OF PLANTS As you just learned, animals have different life cycles. Plants also go through their own life cycles. Two typical examples are those of lima beans and radishes. The Life Cycle of a Lima Bean In Unit 2 (on pages 75 to 79), you did an experiment with a lima bean plant. This plant was first grown in Central America. Lima bean plants, like all plants, have their own life cycles. Seed. A lima bean plant s life cycle starts with the planting of a seed. Instead of growing inside a fruit, lima bean seeds grow inside a long, curved pod. Each seed, or bean, is flat and round. The bean has two identical sides. Between them is a tiny plant, or embryo. In order to grow, a seed has to be planted and watered.

25 266 Mastering the Grade 4 Science TeKS Germination. The water causes the small plant inside the bean to grow or germinate. Germination occurs when the tiny plant uses the food in the bean to grow. The hard shell around the lima bean bursts open and a root starts to grow downward from the bean into the ground. Seedling. Slowly, the bean is lifted above the ground and a stem appears on the lima bean plant. Its roots help to anchor the plant to the ground. After several days, leaves appear on the stem and grow towards the sunlight. The plant has become a seedling. Adult Plant. The leaves conduct photosynthesis, giving the plant more food to grow. Over time, the new plant becomes mature. It then produces buds at its growing tips. These buds eventually open into flowers on the plant. Bees and other flying insects rub pollen (a powdery substance) on the insides of the flowers of the plant. Lima pods with seeds begin to grow soon after. After a few days, the lima pods ripen. The ripe pods spring open and shoot the seeds out and away from the parent plant. If the seeds fall to the ground, each may grow into a new plant. Then, the cycle begins again. A lima bean pod showing its seeds. ACTING AS AN AMATEUR SCIENTIST Make your own diagram showing the life cycle of a lima bean plant. Your teacher may have a lima bean plant in your classroom. In this case, create your drawing from your own observations.

26 The Life Cycle of the Radish Have you ever eaten a radish? It looks like a little red ball with white, crunchy insides. Some people cut radishes into slices to add to their salads. Radishes were first developed in China. The part that people eat is actually the root of the plant. Like lima bean plants, radish plants go through a life cycle of several stages. LESSON 18: Life Cycles and Heredity 267 Seed. A lima bean plant starts as a tiny seed. Like lima beans, radish seeds actually grow in a pod. The seeds fall to the ground. Germination. A radish seed may germinate very quickly after it is planted. The seed begins to grow. It pushes a root downward into the ground. The root also pushes the seed upward as it grows larger. Part of it becomes the stem. Seedling. Next, the stem begins to grow leaves. The first leaves are small, but the leaves grow longer and broader as the plant continues to grow. Adult Plant. It usually takes about 30 to 40 days for a radish plant to go from a seed to an adult plant. As the plant matures, its main root also grows larger. The root grows round and darker in color. The adult plant also has flowers. A radish plant can only reproduce if its flowers are rubbed with pollen from another radish plant. Bees and other flying insects often bring the pollen from one plant to another. A mature radish. A radish seedling. An adult radish plant. Applying What You Have Learned On the next page, examine the pictures from the life cycle of a radish plant. They are not arranged in correct order. Rearrange these in correct order by copying each picture or cutting it out and pasting it in its proper place.

27 LESSON 18: Life Cycles and Heredity 271 Human parents often try to teach their offspring special behaviors to be like themselves. For example, your parents may have taught you proper table manners. They showed you how to use a knife and fork correctly when eating. They may have taught you to say thank you if someone does something nice to you. In school, you learned to read. The skill of being able to read is not something you inherited from your parents. Instead, you had to work hard to learn this ability. It is a behavior you were taught. The same is even true of some skills for animals. For example, trainers can work hard for many months to teach animals a new skill. With practice, a seal can even be taught to balance a ball on its nose. Learning with Graphic Organizers Complete the graphic organizer below. Likenesses between Parents and OfFspring Inherited Traits Learned Behavior What is it? What is it? Example: Example:

28 LESSON 18: Life Cycles and Heredity 273 CHECKING YOUR UNDERSTANDING Directions: Put a circle around the letter that best answers the question Which is the correct order for the life cycle of this butterfly? A C B4.10C B D Examine The Question. This question asks you to find the correct order for the life cycle of a butterfly. Recall What You Know. You should recall the stages in the life cycle of a butterfly. A butterfly goes through a complete metamorphosis. When its egg hatches, a larva (caterpillar) comes out. The larva later becomes a pupa. Out of the pupa comes the adult butterfly. Apply What You Know. The correct choice must start with the egg, so Choice B and Choice D must be wrong. Choice A is also wrong. It shows an adult butterfly before a pupa. The best answer is Choice C, since it shows the egg, the larva, the pupa, and the adult in correct order. Now try answering some additional questions on your own. 2 Which is a characteristic that a student could learn from his parents? F blue eyes Examine The Question G brown hair Recall What You Know H long, thin fingers Apply What You Know J politeness to adults B4.10B 3 Which example describes a likeness inherited from parents? A Mrs. Smith is five feet tall. B4.10B B John talks very fast. C Dewayne runs to school. D Alice fell and broke her wrist.