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shake the foundations of understanding and lead to new modes of thinking. Thomas Kuhn, philosopher of science, called such discoveries paradigm shifts. Here are some major advances in science. ■ 420 B.C.: Hippocrates begins the scientific study of medicine by maintaining that diseases have common causes. ■ 260 B.C.: Archimedes discovers the principle of buoyancy. ■ 180 A.D.: Galen studies the connection between paralysis and severance of the spinal cord. ■ 1473: Copernicus proposes a heliocentric system. ■ 1581: Galileo finds that objects fall with the same acceleration. ■ 1611: Kepler discovers total internal reflection and thin lens optics. ■ 1620: Francis Bacon discusses the principles of the scientific method. ■ 1687: Newton formulates the laws of gravity. ■ 1789: Lavoisier states the law of conservation of energy. ■ 1837: Darwin uses natural selection to explain evolution. ■ 1864: James Clerk Maxwell shows that light is an electromagnetic phenomenon. – HISTORY AND NATURE OF SCIENCE– 260 N OW THAT YOU have reviewed the information you need to know, it’s time to think about strategies you can use at test time. Throughout this chapter, you will review the structure of the science exam and learn specific tips you can use to improve your score on the test. Read this chapter carefully, and then review your notes from the science section. When you are ready, move on to the practice questions that follow.  Multiple-Choice Questions The good thing about multiple-choice questions is that the answer is right in front of you. All you need to do is find it, or at least eliminate some of the clearly wrong choices. At times, you may not be able to eliminate all four of the incorrect choices. But there is no penalty for guessing on the GED. If you can eliminate one of the wrong choices, you will have a 25% chance of guessing correctly, and that is still better than leaving it blank. If you can eliminate three choices, you have a 50% chance of getting the question right. When answering multiple-choice questions, make sure you have read the question carefully. Often, the question will ask you to chose a statement that is NOT true or find an exception to the rule. CHAPTER Tips and Strategies for the GED Science Exam IN THIS chapter, you will briefly review some tips you can use on the GED Science Exam. Several tips apply to other sections of the GED as well. 29 261 Even when you think you have found the correct choice, quickly glance at the other choices to make sure that no other choice is better or more specific. Also, check whether one of the choices is “All of the above.” You may well have picked out a correct statement, but if the rest of the statements are also correct, the answer needs to be, “All of the above.”  Types of Questions Two types of questions appear on the GED—conceptual understanding and problem solving. Conceptual understanding questions require you to read and understand the information provided or to recall basic knowledge you have acquired through prior schooling or everyday life. Read the question and information provided along with it carefully. Often, a question will ask you to restate what was already said or to make a generalization about the facts presented in a passage. By reading carefully and making notes on a piece of scratch paper as you go along, you increase your chances of understanding the provided information correctly. Problem-solving questions require you to apply what you have read or learned. As you are studying for the exam, when presented with a scientific fact, such as “energy can be converted from one form to another,” think about the situations in which that fact is apparent. Think about a car—using the chemical energy in the fuel causes the car to move and the engine to heat. Think about how the fuel level decreases as the car moves. Where is the fuel going? What is happening to the exhaust gases? The principles of science are all around you. By paying attention to them in your everyday life, you will be better prepared to answer problem-solving questions on the GED.  Reading and Understanding Graphics About half of all GED Science questions include graphics. By becoming familiar with different types of graphics and learning about their essential components, you will be better prepared to answer GED Science questions that contain graphical information. When looking at a chart or a graph, look at the title or caption first. This will give you an overview of what the graphic is showing. Next, look at any legends or axis labels provided. This will give you an idea of what variables are shown. Make a list of the variables. Once you have done that, you can try to interpret the chart or graph by noting any trends you may see. How is one variable changing in response to the other? Next, you can read the question and attempt to answer it. Here is more specific information about graphics. Charts All charts are composed of rows (horizontal) and columns (vertical). Entries in a single row of a chart usu- ally have something in common, and so do entries in a single column. Determine what the common elements are when you try to answer the questions on the GED Science Exam. Graphs Three common types of graphs are scatter plots, bar graphs, and pie graphs. This section provides a brief description of each. Whenever a variable depends continuously on another variable, this dependence can be visually represented in a scatter plot. An example includes a change in a property (such as human population) as a function of time. A scatter plot consists of the horizontal (x) axis, the vertical (y) axis, and collected data points for variable y, measured at variable x. The variable points are often connected with a line or a curve. A graph often contains a legend, especially if there is more than one data set or more than one variable. A legend is a key for interpreting the graph. Look at the sample graph above. The essential elements of the graph—the x- and y-axes—are labeled. The legend to the right of the graph shows that dots are used to represent the variable points in data set 1, Graph Title 100 120 140 80 60 40 20 0 0246810 data set 1 data set 2 y-axis x-axis – TIPS AND STRATEGIES FOR THE GED SCIENCE EXAM– 262 while squares are used to represent the variable points in data set 2. If only one data set exists, the use of a legend is not essential. Bar graphs are similar to scatter plots. Both have a variable y plotted against a variable x. However, in bar graphs, data is represented by bars, rather than by points connected with a line. Bar graphs are often used to indicate an amount or level, as opposed to a continuous change. Pie graphs are often used to show what percent- age of a total is taken up by different components of that whole. Diagrams Diagrams could be used to show a sequence of events, a chemical or biological process, the setup of a science experiment, a phenomenon, the relationship between different events or beings, and so forth. When you see a diagram, first determine its purpose. What is it trying to illustrate? Then, look at the different labeled parts of the diagram. What is their function? How are they interrelated?  Reading and Understanding Scientific Passages When reading a scientific passage, the most important thing is to focus on the big picture, or on the subject of the passage. In many ways, the reading passages in the science part of the GED are the same as the reading passages in other areas. One important difference is that science passages may expose you to science jargon, specialized vocabulary you may not be familiar with. Try not to let new words throw you off. You may be able to guess their meaning from the context. Even if you can’t, keep reading. The questions following the passage may not require you to understand that particular word.  Series of Questions Based on a Passage or Graphic On the GED, you will sometimes be asked more than one question based on the same graphic or passage. When this is the case, it is worth your while to invest a little more time to understand the graphic or passage. Even if you are unsure about the first one, try answering the remaining questions—they may be easier for you.  Experiment Skills Experiments should be designed and conducted in accordance with the principles of the scientific method. This means that the goal of the experiment should be carefully formulated and the experiment should be set up to yield factual results. Review the concepts of the scientific method in Chapter 22 if the tips included in this section are unfamiliar to you. Setting Up an Experiment Experiments should be set up to test one clearly formulated and testable hypothesis. The number of variables (things changing) in the experiment should be limited and carefully controlled. If possible, experiments should contain a control group. For example, if you were to study the effect of a new soil supplement on house plants, the soil supplement should not be used on a few plants, which will comprise the control group. If there is improvement in the growth of only the plants on which the supplement was used, then there is strong indication that the supplement increases the plant growth. If, however, the plants in the control group grow as much as the plants on which the supplement was used, then the causes of growth most likely are not linked to the supplement. In this example, there would be two variables— the use of the supplement and the plant growth. How the supplement is administered and how plant growth is measured would need to be carefully described and controlled. For example, the scientist conducting the experiment would need to decide whether the supplement would be administered once, several times, or every day throughout the experiment. The scientist would also need to define what constitutes plant growth—the vertical increase, the number of new leaves, the growth of new branches and leaves, or some combination of these factors. One choice is not necessarily better than the others. Measuring the vertical growth wouldn’t necessarily be worse than counting the number of new leaves. Sci- entists must be consistent. If the number of leaves is recorded one day on one plant, it should be recorded every day on all the other plants in the experiment. On the GED, you may be asked to pick out the best design for an experiment. Before you look at the choices, determine the important variables and what would make a good control. Select the choice that contains these variables, that has the most logical experimental control, and in which the variables not studied are held constant. – TIPS AND STRATEGIES FOR THE GED SCIENCE EXAM– 263 Interpreting Others’ Results In some GED questions, you will be asked to interpret others’ results. You will need to make a generalization about the results or draw a conclusion. Don’t base your answer of what you believe is right. Base your answers on the results provided. Look at the choices given. Some could be inaccurate—if one part of the result doesn’t fit the description in the choice, the choice is wrong (unless words such as generally or in most cases make room for exceptions). Make sure you don’t jump to conclusions. A trend doesn’t always indicate a cause and effect relationship. For example, every morning, your alarm clock goes off, and every morning, you get hungry. However, the alarm clock is not what is making you hungry. The two events just happen to occur at the same time. Before you conclude that there is a cause and effect relationship on the GED, consider other conclusions, and then pick the most logical one. Analyzing Experimental Flaws A common GED Science question requires you to ana- lyze the flaws of an experiment. Experiments should be based on the scientific method. Common experimental flaws include: ■ not testing the hypothesis ■ having too many variables ■ unforeseen variables ■ lack of experimental control ■ jumping to conclusions Applying Scientific Conclusions What good is science if we don’t benefit from it? How would the finding that keeping a laptop on your lap for too long can damage your pelvic organs influence you? You would not keep the laptop on your lap for too long, right? Many questions on the GED require you to apply a scientific conclusion, either to your personal life or to global phenomena. These are almost always questions from the problem-solving category. You are presented with a fact in one context and asked to apply it in another context. For example, if you read in a passage about different methods of determining the sides of the world in nature without a compass, you could be asked which of the methods would best work if you were in a particular situation—lost on a cloudy night in a forest, on the ocean on a clear day, etc. If necessary, as you are reading information provided in the question, make quick diagrams and summarize the important concepts on a piece of scrap paper. These strategies may help you visualize the concepts or the given situation and could help you make sense of the question.  Other Useful Skills The more material you are exposed to, the easier it will become to understand it. Reading about science and applying science takes practice, just like riding a bike. At first, you may be a bit clumsy with it, but if you stick with it, you improve rapidly and it begins to click. To compre- hend science better, read as much about science as you can—in newspapers, magazines, and on the Internet. Make sure you look at graphics, as well. As you are reading, think about what the passage or graphic, is commu- nicating to you. What are the possible applications of the science concepts discussed? What can you conclude based on the information given? What methods were used to arrive at the facts presented? Is anything presented an opinion or belief rather than a fact? Try to make up questions about the passage or graphic you read. Imagine that you are making up the GED: What could you ask the stu- dents? By anticipating the move of your opponent, you are better prepared to respond to it. – TIPS AND STRATEGIES FOR THE GED SCIENCE EXAM– 264  Directions Read the questions carefully and choose the best answer for each question. Some questions may refer to a passage, illustration, or graph. Be sure to answer every question; you will not be penalized for incorrect answers. Do not spend too much time on any one question so you can be sure to complete all the questions in the allotted time. Record your answers on the answer sheet provided on page 267. Make sure you mark the answer in the circle that corresponds to the question. Note: On the GED, you are not permitted to write in the test booklet. Make any notes or calculations on a sep- arate piece of paper. CHAPTER GED Science Practice Questions NOW IT’S time to put all that you have learned about science and scientific inquiry into practice. In the following section, you will find 75 multiple-choice questions like those you will find on the GED Science Exam. 30 265