2 ND EDITION. Science

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1 2 ND EDITION 5 6 Science

2 TABLE OF CONTENTS Introduction... 1 General Tips for Taking Science Tests... 2 Unit 1 The Nature of Science... 5 Review 1: Scientific Knowledge... 6 Science Standards and Concepts: NS.A.1 4, NS.A.6, NS.A.7 Review 2: Scientific Investigation Science Standards and Concepts: NS.A.5, NS.B.1 4, NS.B.10 Review 3: Reporting and Interpreting Data Science Standards and Concepts: NS.B.5 9 Review 4: Technology and Society Science Standards and Concepts: NS.C.1 3, NS.D.1 5 Unit 2 Physical Science Review 5: Physical Properties and Changes Science Standards and Concepts: PS.A.1, PS.A.3, PS.A.4 Review 6: Chemical Properties and Changes Science Standards and Concepts: PS.A.2, PS.A.3, PS.A.5, PS.A.6 Review 7: Energy Transformations and Resources Science Standards and Concepts: PS.B.1, PS.B.2, PS.B.4 7 Review 8: Electricity Science Standards and Concepts: PS.B.2 4 Review 9: Motion and Force Science Standards and Concepts: PS.C.1 4 Unit 3 Earth and Space Science Review 10: Climate and Weather Science Standards and Concepts: ESS.A.1 4, ESS.C.1 Review 11: Minerals, Rocks, and Soil Science Standards and Concepts: ESS.B.1 4 Review 12: Patterns in Outer Space Science Standards and Concepts: ESS.C.1 5 Unit 4 Life Science Review 13: Cells and Systems Science Standards and Concepts: LS.A.1 3 Review 14: Reproduction and Traits Science Standards and Concepts: LS.B.1 3 iii

3 Table of Contents Review 15: Adaptation and Species Survival Science Standards and Concepts: LS.C.1 4, LS.D.5, LS.D.6 Review 16: Ecosystems Science Standards and Concepts: LS.D.1 4, ESS.A.4 Appendix Glossary To the Teacher: Science Standards and Concepts codes are listed for each review in the table of contents and for each page in the shaded gray bars that run across the tops of the pages in the workbook (see example to the right). These codes indicate which Buckle Down science standards and concepts are covered in a given review or on a given page. iv

4 Unit 1 The Nature of Science Science Standards and Concepts: NS.A.1, NS.A.4, NS.A.7 Review 1 Scientific Knowledge Have you ever wondered how a TV works? Have you ever wondered why water boils when put on a hot stove? Or have you ever wondered why peacocks have such large, bright feathers? If so, then you have thought like a scientist. Scientists look at the world around them, ask questions, and seek answers to those questions. They observe the world around them by noticing details, such as the different shapes of tree leaves. Then they make predictions and try to explain what they see, such as someone trying to find out who left a trail of muddy footprints on a kitchen floor. Finally, they test their predictions by designing experiments, similar to the way you might mix different foods together to get a different taste. Every day, we think and act like scientists, usually without even realizing it. The Scientific Method If you believed everything that you saw about scientists in movies or on TV, you might think scientists were a strange bunch. Some shows present scientists as crazy geniuses who make amazing things, such as endlessly bouncing rubber balls or flying cars. These scientists don t seem to follow any particular method; their ideas just come to them. In other shows, scientists are unimaginative people who only follow a set of instructions, like a robot following a program. Such scientists follow a too-rigid version of what is sometimes called the scientific method. If you take these images too seriously, you come to a disappointing conclusion: Only a genius or a total bore could ever become a scientist. Describe a scientist that you remember from movies, TV, or comic books. What does that character tell you about scientific research? Words to Know continental drift experiment Pangaea scientific method variable

5 Science Standards and Concepts: NS.A.1, NS.A.3, NS.A.4, NS.A.7 Review 1: Scientific Knowledge We ve got news for you: Movies and TV don t give you the whole picture. Most scientists aren t nutty professors or soulless robots, and the scientific method is not the same thing as a computer program. In fact, scientists are like most people: They re curious about the world around them and interested in how things work. Scientific work can be very imaginative. It took imagination to figure out that the Earth travels around the Sun, or that tiny germs make large creatures sick, or that the continents move over time. True, scientists follow steps when investigating a problem or doing experiments, but those steps are flexible. Instead, the guiding forces behind those steps are curiosity and keeping an open mind. Sometimes scientific investigations seem like step-by-step recipes. Other times, they are more like mystery stories. What are some differences between a recipe and a mystery story? Curiosity and imagination are vital to scientific discovery, but they are only part of the story. Sherlock Holmes, the great detective, couldn t just sit in his chair and solve a case. (Well, not always.) He used his eyes, ears, and nose to find clues. He also did research by reading books and talking to people. In short, he combined his desire to know with observations and prior knowledge. Scientists do the same thing. Developing Scientific Knowledge The story of Alfred Wegener, a German scientist, is a good example of one way in which scientific knowledge forms. It also demonstrates how science can be a mystery that requires open-mindedness, imagination, and careful observation to solve. During a lecture in 1912, Wegener proposed the idea of continental drift, which states that continents move over time and were once joined together in a huge landmass called Pangaea. This was a pretty imaginative idea. After all, the continents are some of the biggest things on Earth, so what could possibly move them around?

6 Unit 1 The Nature of Science Science Standards and Concepts: NS.A.1, NS.A.3, NS.A.4 Arctic Ocean Pacific Ocean NORTH AMERICA Atlantic Ocean EUROPE AFRICA ASIA 0 Equator SOUTH AMERICA Indian Ocean AUSTRALIA ANTARCTICA Look at the world map above. Describe one thing on the map that might suggest the continents were once joined together. Wegener knew that such a bold idea would have to be supported by many observations. He saw that South America and Africa fit together pretty well, and noted that the southeast coast of the United States might fit with northwest Africa. However, other people had already made these observations, but few people believed that the continents moved; Wegener needed more evidence. Through his research, he learned that the bones of a large reptile that lived millions of years ago had been found in both Africa and South America. It was unlikely that this animal swam across the Atlantic Ocean, so why was it on both continents? He also learned that fossils of an ancient plant had been found in Africa, South America, and Antarctica. This plant grew only in warm, dry conditions; what was it doing on a frozen continent? From these (and other) observations, Wegener proposed that the continents had been joined together to form Pangaea, as shown in the map on page 9.

7 Science Standards and Concepts: NS.A.1, NS.A.3, NS.A.4 Review 1: Scientific Knowledge Pangaea: The Supercontinent Pangaea Equator Imagine that you re a scientist who disagrees with Wegener s idea. What other ways could animals and plants have been spread among the continents? Most scientists disagreed with Wegener s ideas because they seemed too fantastic. Some pointed out that he did not say what force made the continents move. Wegener replied that the Moon s gravity, which causes the Earth s tides, could move the continents. Another scientist did some experiments to test this idea. He found that the Moon s gravity could not provide enough force, so there was still no explanation as to why the continents moved. Do you think that Wegener failed as a scientist by not proposing a force that could successfully cause continental drift? Explain your answer.

8 Unit 1 The Nature of Science Science Standards and Concepts: NS.A.1 4, NS.A.6 It might seem that Wegener s story is an example of science gone wrong. After all, most scientists now accept the idea that the continents move. If Wegener was right, why wasn t he believed back in 1912? Did Wegener fail to state his observations and conclusions clearly enough? Were the other scientists being foolish or mean-spirited? No. In fact, the other scientists were doing exactly what good scientists do: They questioned Wegener s ideas, tried to fit his observations into what they already knew, and tested his conclusions with experiments. This process is extremely important in forming valid scientific knowledge. After all, Wegener s idea did have some problems with it, including the big one: What could make the continents move? Until this problem was resolved, continental drift made for good science fiction, not good science. (In Review 2, you ll read why Wegener s ideas were finally accepted.) Why is it important for many scientists to examine the observations and conclusions of one scientist? Variables Most scientific investigations aren t quite as big as continents sliding across the planet. Scientific work usually involves answering small but interesting questions, often by conducting experiments in labs. But big or small, all scientific investigations share some basic features. Probably the most important feature is keeping track of all factors that might affect the results of an investigation or experiment. These factors are called variables. The word variable comes from a Latin word meaning to vary or change. In science, a variable is a characteristic that changes over time and under different conditions. For example, when an ice cube melts, several of its characteristics change. The temperature of the water rises, the shape of the water changes, and the volume of the water decreases a bit. Variables are important because all science is concerned with the issue of change. Scientists want to learn how things change, explain why things are the way they are, and predict how things might be in the future. 10

9 Science Standards and Concepts: NS.A.1 3, NS.A.6 Review 1: Scientific Knowledge Why is it important for scientists to keep track of variables in their experiments? In a recipe, all of the variables (such as quantity, temperature, and time to cook) are given ahead of time. In an experiment, the variables are not always so obvious. There are many variables that can affect an experiment. It is difficult to keep track of them all, but scientists have to try so that they can explain their observations. Sometimes an unnoticed variable can change an experiment and give false results. Because of this, scientists try not to get too excited (or too disappointed) by one result. For example, Dr. Beckett is studying the amount of oxygen in a lake. The weather has been hot lately, which could be bad: Warm water cannot hold as much oxygen as cold water, and just like you, fish need oxygen. The fish might have trouble breathing. Dr. Beckett wants to find out if the amount of oxygen in the water changes during the day. She predicts that the water will contain more oxygen in the morning when it is cool, and less oxygen in the afternoon when the water heats up. She takes one morning water sample and another sample in the afternoon, and then she compares the amounts of oxygen in each. What variable(s) is Dr. Beckett examining? After testing the two water samples, Dr. Beckett is surprised: The water from the afternoon actually has more oxygen than the water from the morning. She tells a colleague about her experiment. Working together, they repeat the experiment and get the same result. They talk, share their knowledge, and realize that she missed at least one important variable. Not only did the Sun increase the temperature of the lake water, it also increased the rate at which plants in the lake produced oxygen. In the afternoons, lake plants produced enough oxygen to make up for any oxygen lost from the heated water. 11

10 Unit 1 The Nature of Science Science Standards and Concepts: NS.A.1 3, NS.A.6 Why is it important for scientists to work together and share knowledge? When scientists get a clear result from an experiment, they make sure that they don t try to make the result say more than what it really tells them. For example, suppose that Dr. Beckett concludes that it doesn t matter how warm the lake gets. The lake plants produce more oxygen in the afternoon when the Sun is overhead, so the fish will always be able to breathe. How might Dr. Beckett s conclusion be mistaken? After running many experiments, most scientists learn that it is important not to get too excited by any interesting results. One single example can never prove that something is always correct. Even though an exciting or interesting result may come up after one experiment, that doesn t mean it will always occur. A scientist s work is never finished, just as the scientific mission will never be completed. There will always be something interesting to explore just around the corner. This is one reason why so many curious people enjoy science. Furthermore, even those scientific ideas that are generally accepted might still be able to provide some surprises. For example, most scientists accept the idea that the Earth s climates change over time. The idea of ice ages, when glaciers cover much of the Earth s surface, is well-accepted. But some scientists have come up with a surprising twist on this idea. They have found evidence that, in the distant past, the entire planet was completely covered in ice even near the equator, where it is now very warm. This idea, referred to as snowball Earth, is being debated in the scientific community. Only through further observations and experiments will the scientific community come to accept, reject, or change the idea. Remember this: Scientific thinking is neither pure recipe nor pure mystery. It does follow some rules, but it is also flexible. Thinking like a scientist does not mean that you have to become a crazy genius or a robot. It means looking at the world, being curious about why things are the way that they are, and coming up with different ways to answer questions that interest you. The questions can be big ( Why do the continents look the way they do? ) or small ( How much oxygen can a drop of lake water hold? ). Exploring such questions means that you are thinking like a scientist. 12

Science Standards and Concepts: NS.A.1 3, NS.A.6 Review 1: Scientific Knowledge Keys to Keep Scientific knowledge is always growing and changing with new discoveries.

11 Science Standards and Concepts: NS.A.1 3, NS.A.6 Review 1: Scientific Knowledge Keys to Keep Scientific knowledge is always growing and changing with new discoveries. The scientific method is flexible. You can alter it to fit a specific investigation. Scientists should question and verify results from other scientists. Variables are the factors that can change in an investigation. These need to be identified in order to have accurate results. Curiosity and open-mindedness are important qualities for a scientist to have. Profiles in Science It might seem amazing that one of the animals Charles Darwin studied in the 1830s could have lived until But giant tortoises can live that long. Although there is disagreement about whether Harriet was actually one of Darwin s tortoises, scientists do know that she lived to be 176 years old. Harriet was a giant tortoise from the Galapagos Islands. These islands are located off the west coast of South America. Harriet is supposedly one of the tortoises that Charles Darwin studied and brought back from the Galapagos Islands in She lived in Britain for a few years and then Australia for most of her life. Darwin was one of the world's most famous scientists. He is best known for his studies on the theory of evolution. Evolution says that all species are able to change over time, or evolve, in response to their surroundings. This happens, as he explained, because the individuals with more successful traits and body structures survive and then pass these traits on to their offspring. The weaker individuals, therefore, are not able to survive and do not produce offspring. The tortoises that he studied from the Galapagos Islands showed strong evidence of evolution. Harriet the Tortoise ( ) 13

12 Unit 1 The Nature of Science Science Standards and Concepts: NS.A.2, NS.A.6 Explore It Yourself In this activity, you will experiment with different variables and see how they affect the rotation of an object. If an object has more of its mass on its outer edges, will it spin faster or slower? Your teacher will give you a 12-inch ruler, 2 small binder clips, 2 large binder clips, and 60 cm of string. Step 1: Attach the small binder clips to each end of the ruler. Tie the string to the loops on the binder clips. Put the two large binder clips next to each other in the center of the ruler. When finished, the setup should look like the diagram to the right. Step 2: Hold up the ruler by looping the string over a pencil. Make sure the ruler is balanced. Wind the string by making 10 complete revolutions of the ruler. Step 3: In the following three trials, you will time how long it takes for the string to completely unwind. Start the stopwatch when the ruler begins to spin. Stop the stopwatch at the instant the string stops unwinding. Do not include any time that the string, through the ruler s momentum, spends rewinding itself. Trial 1: Release the string and allow the ruler to spin. Time how long it takes for the string to completely unwind. Record the value in the table at the bottom of the page. Trial 2: Move each large binder clip so that the middle of one is at the 3-inch mark and the middle of the other is at the 9-inch mark. Wind up the string as before. Time how long it takes for the string to completely unwind, and record the value. Trial 3: Move the large binder clips to the ends of the ruler. Wind up the string as before. Time how long it takes for the string to completely unwind, and record the value. Time for String to Unwind Clips at Center Clips Between Edges Clips at Edges of Ruler (s) and Center of Ruler (s) of Ruler (s) 14

13 Science Standards and Concepts: NS.A.2, NS.A.6 Review 1: Scientific Knowledge What Does It Mean? 1. Compare the time it took for the string to unwind in each of the three trials. What are the differences among the three trials? 2. Write a general rule describing how the placement of mass affects the speed at which an object rotates. 3. Toby decides to use a meterstick instead of a ruler. He keeps everything else the same and times it to see how long it will take to unwind. Will the same general rule you wrote in Number 2 still apply to the meterstick? Do you think the meterstick will take more time or less time to unwind than the ruler? Why? 15

14 Unit 1 The Nature of Science Science Practice 1. Which of the following phrases best describes the scientific method? A. correct laboratory procedures B. a set of rules on how to act like a scientist C. a flexible approach to learning about the world D. a step-by-step way to get the right answer each time 2. To support his theory of continental drift, Alfred Wegener proposed that the Moon pulled on the continents and made them move slowly. This was proven to be incorrect. What does this suggest about the way that scientific knowledge forms? A. The crazier an idea is, the more likely it is that the idea is true. B. A scientist cannot be truly successful if he or she makes a false proposition. C. Scientists need the help of other scientists to help correct the mistakes in their ideas. D. Some scientists are too heavily influenced by the forces of the Moon, and they should be ignored. 3. A scientist says that he has performed an experiment that turns lead into gold. How should other scientists respond to this claim? A. They should give the scientist more funding to continue his work. B. They should make fun of the scientist for such a crazy idea. C. They should try the experiment themselves and compare their results. D. They should try similar experiments, like turning copper into silver. 16

15 Review 1: Science Practice 4. How is scientific thinking helpful in everyday life and in nonscientific careers? A. Everyone must pass science tests throughout their lives. B. Scientific thinking can help you avoid making false assumptions. C. Scientific-sounding explanations cause more people to believe you. D. Every question in life can be answered by using the scientific method. 5. Imagine your class had a contest to see who could make the best paper airplane. Everyone in the class will make an airplane. Then each person will throw his or her airplane. The longest throw wins. What are three variables that could affect the results of this contest? _ 6. Albert Einstein, one of the greatest scientists of the 20th century, said the following about science: No number of experiments can ever prove me right, but a single experiment can prove me wrong. What did Einstein mean? 17

Exploring Science Grades K-2

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