To access a customizable version of this book, as well as other interactive content, visit www.ck12.org CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the FlexBook®. CK-12 intends to pioneer the generation and distribution of high-quality educational content that will serve both as core text as well as provide an adaptive environment for learning, powered through the FlexBook Platform®. Copyright © 2012 CK-12 Foundation, www.ck12.org The names "CK-12" and "CK12" and associated logos and the terms "FlexBook®" and "FlexBook Platform®" (collectively "CK-12 Marks") are trademarks and service marks of CK-12 Foundation and are protected by federal, state and international laws. Any form of reproduction of this book in any format or medium, in whole or in sections must include the referral attribution link http://www.ck12.org/saythanks (placed in a visible location) in addition to the following terms. Except as otherwise noted, all CK-12 Content (including CK-12 Curriculum Material) is made available to Users in accordance with the Creative Commons Attribution/Non-Commercial/Share Alike 3.0 Unported (CC-by- NC-SA) License (http://creativecommons.org/licenses/by-nc-sa/3.0/), as amended and updated by Creative Commons from time to time (the "CC License"), which is incorporated herein by this reference. Complete terms can be found at http://www.ck12.org/terms. ISBN :__isbn_number__ Authors Jean Â​Brainard, (JBrainard), Julie Â​Sandeen, (JSandeen) Say Thanks to Authors Click http://ck12.org/saythanks (No Sign in required) MS What is Earth Science? Earth Science is all about the Earth: its land, its water, its atmosphere. It’s about Earth’s resources and about the impacts human activities are having on all of those things: the land, water, and atmosphere. Earth Science is even about the vastness that surrounds the planet: the solar system, galaxy, and universe. So can we say Earth Science is about everything? Well, not really, but it is a science that encompasses an awful lot. Note the word science in that last sentence. Earth Science is a science, or maybe it’s made up of a lot of sciences. But what is science? Most people think of science as a bunch of knowledge. And it is. But science is also a way of knowing things. It’s different from other ways of knowing because it is based on a method that relies on observations and data. Science can’t say how many angels can dance on the end of a pin because that question can’t be tested. In fact, science can’t even say if there are such things as angels for the same reason. For something to be science, it must be testable. And scientists are the people who do those tests. The Nature of Science Lesson Objectives Why is it important to ask questions? How can you use the steps of the scientific method to answer questions? How do scientists make models? What steps should you take to be safe while you are doing science? Vocabulary control dependent variable hypothesis independent variable physical model theory Introduction Sometime in your life you've asked a question about the world around you. Probably you've asked a lot of questions over the years. The best way to answer questions about the natural world is by using science. Scientists ask questions every day, and then use a set of steps to answer those questions. The steps are known as the scientific method. By following the scientific method, scientists come up with the best information about the natural world. As a scientist, you need to do experiments to find out about the world. You also need to wonder, observe, talk, and think. Everything we learn helps us to ask new and better questions. Scientific Method The scientific method is a set of steps that help us to answer questions. When we use logical steps and control the number of things that can be changed, we get better answers. As we test our ideas, we may come up with more questions. The basic sequence of steps followed in the scientific method is illustrated in Figure below . Figure 1.1 The Scientific Method. Questions Asking a question is one really good way to begin to learn about the natural world. You might have seen something that makes you curious. You might want to know what to change to produce a better result. Let’s say a farmer is having an erosion problem. She wants to keep more soil on her farm. The farmer learns that a farming method called “no-till farming” allows farmers to plant seeds without plowing the land. She wonders if planting seeds without plowing will reduce the erosion problem and help keep more soil on her farmland. Her question is this: “Will using the no-till method of farming help me to lose less soil on my farm?” ( Figure below ). Figure 1.2 Soil is often lost from ground that has been plowed. Research Before she begins, the farmer needs to learn more about this farming method. She can look up information in books and magazines in the library. She may also search the Internet. A good way for her to learn is to talk to people who have tried this way of farming. She can use all of this information to figure out how she is going to test her question about no-till farming. Farming machines are shown in the Figure below . Figure 1.3 Rather than breaking up soil like in this picture, the farmer could try no-till farming methods. Hypothesis After doing the research, the farmer will try to answer the question. She might think, “If I don’t plow my fields, I will lose less soil than if I do plow the fields. Plowing disrupts the soil and breaks up roots that help hold soil in place.” This answer to her question is a hypothesis . A hypothesis is a reasonable explanation. A hypothesis can be tested. It may be the right answer, it may be a wrong answer, but it must be testable. Once she has a hypothesis, the next step is to do experiments to test the hypothesis. A hypothesis can be proved or disproved by testing. If a hypothesis is repeatedly tested and shown to be true, then scientists call it a theory . Experiment When we design experiments, we choose just one thing to change. The thing we change is called the independent variable . In the example, the farmer chooses two fields and then changes only one thing between them. She changes how she plows her fields. One field will be tilled and one will not.