Name ______Class ______Date ______
TEKS 2AThe student is expected to know the definition of science and understand that it has limitations, as specified in subsection (b)(2) of this section: "Science, as defined by the National Academy of Sciences, is the ‘use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process.’ This vast body of changing and increasing knowledge is described by physical, mathematical, and conceptual models.
Students should know that some questions are outside the realm of science because
they deal with phenomena that are not scientifically testable."
TEKS LESSON 2A: Understanding Science
What is science?
Science is the use of evidence to construct testable explanations and predictions of natural phenomena. Science also refers to the knowledge of the natural world generated through this process.
The word science comes from the Latin word scientia, which simply means "knowledge." People can speak of the "science" of hitting a baseball, or library science, or the science of running a hotel. But natural science in the strict sense is something more specific than mere knowledge. Science is the dynamic yet organized process of gathering, testing, and analyzing evidence about the natural world.
What is the process of science?
Don't think for a minute that science is a mysterious process used only by highly trained people. Science is nothing more than an orderly way of asking questions about nature and then trying to answer them. A summary diagram is shown below, followed by a description of each stage.
Observation and InferenceMost scientific investigations begin with observation, the act of noticing and describing events and things in a careful, orderly way. Observations can be made by reading scientific literature or by noticing something in nature. Careful observation leads to questions and sometimes to inferences about what may be happening. An inference is a logical interpretation of things or events based on knowledge that we already have. For example, if a car engine did not start on a very cold morning, you might infer that it had a dead battery, especially if you knew that the battery was several years old and that you had filled up the gas tank the day before.
HypothesisThe next step following observation and inference is to form a hypothesis. A hypothesis is a scientific explanation for observations. The key to forming a good hypothesis is testability. A hypothesis that can be tested, even if it turns out not to be supported by data, can advance scientific understanding. However, a hypothesis that cannot be tested, no matter how provocative, will not help to advance scientific knowledge.
Testing HypothesesHypotheses generate specific statements about what we would expect to observe if the hypotheses were true. Scientists often use models to generate predictions when they cannot observe a phenomenon directly. This is particularly true when the hypothesis concerns events that may have happened in the distant past. For example, the eastern coastline of South America closely matches the western coastline of Africa. This led a number of scientists to wonder if the coastlines could once have been part of the same continent, only to drift apart and be separated by the Atlantic Ocean. Obviously, it is impossible to go back in time to test this hypothesis directly. However, modeling enabled scientists to generate testable predictions. One prediction is that if the two continents had once been joined, the geological layers on both sides of the ocean should line up in the same sequence. Geologists have found that, in fact, they do. Models also predict that if the continents have indeed moved apart, the middle of the ocean floor should show evidence of where they separated. Oceanographers have found evidence to support this prediction, namely the mid-Atlantic ridge. And finally, models predicted that careful measurements of the continents today should show them continuing to drift apart. This prediction, too, is borne out by scientific observations today, giving a high degree of confidence that the hypothesis of continental drift is correct. There are many ways to test predictions, including experimentation and observational studies. Depending on the question being investigated, one type may be more useful—or practical—than the other.
ExperimentationScientific hypotheses can sometimes be tested by carrying out an experiment in which the possible outcomes may support or reject the hypothesis. To do this, the experimenter must keep track of all the factors—the variables—that can change or affect the results. The experimenter then carries out a controlled experiment in which just one variable is changed to test its effect on the results. The results of controlled experiments should be repeatable, which means that additional experiments should give identical results. To be truly testable, a scientific explanation must generate specific predictions that can be supported or rejected by further observations or by the outcomes of controlled experiments.
Observational StudiesFor many scientific questions, controlled experiments are simply not possible. For example, it would be impossible to perform a controlled experiment to test a hypothesis regarding the origin of the universe. In other cases, it is unethical to perform an experiment. A scientist could not, for example, set up an experiment to test the toxicity of a dangerous chemical on humans. When experiments are not possible, scientists may gather data by making observations that might tend to support or reject the hypothesis. Climate scientists, for example, might suggest a hypothesis that the warming of earth’s climate is at least partly due to increasing concentrations of carbon dioxide in the atmosphere. While it isn’t possible to use Earth itself as an experimental system, scientists can look for evidence of temperature and carbon dioxide concentrations in the past to see if they support the hypothesis. One of the ways to gather such data is to examine the composition of ice in glaciers in the polar regions of the planet. Because ice is laid down in a yearly pattern, scientists can examine ice from tens or even hundreds of thousands of years ago. Since atmospheric gases are trapped as the ice forms, such samples provide data on the concentration of carbon dioxide and other gases in the past, and these observations can be used to support or reject hypotheses about the relationship between global climate and the composition of the atmosphere.
Data CollectionScientists collect and record data, or information, from their studies. Science particularly values quantitative data—data expressed using numbers—because numbers provide precision and are easy to compare. Data not expressed using numbers is called qualitative data.
Data Analysis and InterpretationData in the form of both results and observations serves as evidence for scientists to use to test their predictions. If the evidence gathered matches their predictions, the hypothesis is supported. If the evidence gathered does not match their predictions, the hypothesis is contradicted. If the hypothesis is contradicted, the scientists may revise their hypothesis and generate a new set of testable predictions.
What are the limitations of science?
For all of its strengths, science is always tentative. Scientific data, observations, and experiments may support certain hypotheses so strongly that we become virtually certain they are correct. However, this does not mean that such hypotheses are ever considered as “proven.” Science is always open to the possibility that new observations or experiments may contradict an established hypothesis. If that occurs, scientists must be ready first to abandon ideas that do not fit their data and then to construct new, testable hypotheses for further study.
Does the fact that science rarely provides proof that something will or will not happen with absolute certainty mean that information provided by scientific methodology isn't useful? Absolutely not! As scientific hypotheses and theories are tested again and again, they build up evidence that can help to predict the likelihood of different events. How much does smoking tobacco increase the risk of lung cancer and heart disease? How likely is it that a particularly dangerous strain of influenza will spread this year? What is the probability that certain chemicals will negatively affect our health if we ingest them? The predictive power of scientific answers to these questions can help us decide not to smoke tobacco, to vaccinate children against disease, and to remove harmful chemicals from the food supply. Using science, where appropriate, to inform decisions on everything from personal behavior to public policy simply makes good sense.
While science is a powerful method for investigating the natural world, this does not mean that science can be used to investigate every question. Only questions that can be tested against collected data and evidence can be analyzed by science. Science can tell us that organisms are composed of living cells; it can identify the molecules that carry genetic information; and it can even explain how fireflies sparkle on a summer night. But science cannot address questions of the supernatural or questions rooted in personal opinion. Science cannot tell us the meaning of life, determine the value of a work of art, assess the validity of an ethical system, or measure the beauty of a sunset.
The fact that such questions cannot be answered by science does not mean they are unimportant. In fact, many questions that lie outside the realm of science are among the most important issues that concern human societies and individuals. Science, however, is limited—by its own methods and techniques—to statements about the natural world that make testable predictions.
Lesson Check
1.DefineShow that you know the definition of science by writing it below.
Questions 2–6 Each box of information below describes one part of the process of science. Read the information in all of the boxes through once, and then write which stage of scientific methodology is being described in each box. Each stage can be used only once.
testing a hypothesisobservation and inferencedata analysis
formation of hypothesisdata collection
2. Apply ConceptsThe stage of scientific methodology described here is
______
3. Apply ConceptsThe stage of scientific methodology described here is
______
4. Apply ConceptsThe stage of scientific methodology described here is
______
5. Apply ConceptsThe stage of scientific methodology
described here is ______
6. Apply ConceptsThe stage of scientific methodology described here is
______
7.Understand the Limitations of ScienceA student in your class summarizes the results of the study described above by saying, “Researchers proved that nitrogen makes marsh grasses grow taller.” Show that you understand the limitations of science by writing an explanation that explains to that classmate why this summary is inaccurate. Then write a new, accurate summary of the study.
8.Understand the Limitations of ScienceAfter reading the study described above, another classmate proposes a new hypothesis for the researchers to test: Taller salt marsh grasses are prettier than shorter salt marsh grasses. Demonstrating that you understand the limitations of science, explain to this student why this hypothesis is not scientific.
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