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The Nature of Science.ppt

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The Nature of Science.ppt

  1. 1. The Nature of Science
  2. 2. The Nature of Science To be scientifically literate, science students should have deeper understandings of science that studying the Nature of Science (NOS) provides.
  3. 3. Write an account of what you think happened based on what you see here. NOS Example
  4. 4. How does your story change? NOS Example continued
  5. 5. NOS Example How does your story change?
  6. 6. What do you observe? What do you infer? Compare what you think now to your earlier written accounts. NOS Example continued
  7. 7. Some Aspects of NOS • Scientific knowledge is tentative. • Scientific knowledge has basis in empirical evidence. • There is a difference between data and evidence. • Scientific laws and theories are separate kinds of scientific knowledge. • Scientific knowledge is based upon observations and inferences. • Scientific knowledge is heavily dependent upon theories.
  8. 8. Some Aspects of NOS Continued • Scientific knowledge is created from human imagination and logical reasoning. • Scientific knowledge can be obtained by a variety of scientific methods. • Scientific observations are inherently subjective based on interpretations. • Science is a human endeavor influenced by society and culture.
  9. 9. Observation and Inference • There are differences between observations and the inferences made based on observations. • Based on the same data, and scientists’ prior experiences, different inferences can be made, which lead to difference conclusions. Some of these are right and some are wrong. • Attempting to sort this out is what science is about!
  10. 10. Scientific Theory and Scientific Laws
  11. 11. Scientific method • Process used by scientists to solve problems
  12. 12. Theory • In everyday usage, “theory” often refers to a hunch or a speculation. When people say, “I have a theory about why that happened,” they are often drawing a conclusion based on partial or inconclusive evidence. Scientists have hunches, too, but they call them hypotheses, which are the starting point of all good science.
  13. 13. Scientific theory • A scientific definition of theory is quite different from the everyday meaning of the word. A scientific theory refers to a comprehensive explanation of some aspect of nature that unifies a vast body of reliable knowledge. In other words, a theory is born when a substantial number of hypotheses point to the same conclusion
  14. 14. • A simple example of a scientific theory is the Heliocentric Theory which states that the sun is the center of our solar system. Another example would be Cell Theory which states that all living things are composed of cells. Few people would refer to either of these theories as “hunches.” More likely, in everyday language, these theories would be called scientific facts. • In science, a Theory: – Explains a natural phenomenon. – Predicts future occurrences or observations of the same kind. – Can be tested through experiment or otherwise verified through empirical observation. – Is Supported by a vast body of reliable knowledge.
  15. 15. • Reliance on theory is critical to every branch of science. Many scientific theories are so well established that no new evidence is likely to alter them substantially. We all accept that… – the Earth orbits the Sun (heliocentric theory), – living things are made of cells (cell theory), – matter is composed of atoms (atomic theory), and – the Earth's surface is divided into solid plates that move over geological time (theory of plate tectonics). • Each theory has been barraged with scientific tests and still stands intact.
  16. 16. Scientific Law • Contrary to common understanding, scientific theories do not “graduate” to laws… • Scientific laws are typically short, mathematical expressions representing how nature will behave under certain conditions. Most theories contain laws, and more importantly, they explain why laws work and what they mean.
  17. 17. Scientific method • Process that people use to solve problems • Controlled experiment only involves one variable • Control group- is used sometimes and it is used for comparison. • Experimental group Red and blue groups – Ex. Three corn plants used. One is placed in red light, one in blue light, and one is placed in white light. They are observed for two weeks and their growth is recorded.
  18. 18. C. Scientific Method • Hypothesis - testable prediction • Theory - explanation of “why” – based on many observations & experimental results • Scientific Law - prediction of “what” – describes a pattern in nature
  19. 19. C. Scientific Method Theories and laws are well-accepted by scientists, but... They are revised when new information is discovered. THEY ARE NOT SET IN STONE!
  20. 20. C. Scientific Method 1. Determine the problem. 2. Make a hypothesis. 3. Test your hypothesis. 4. Analyze the results. 5. Draw conclusions.
  21. 21. C. Scientific Method 1. Determine the problem. When the Titanic sank, what happened to the water level on shore? 2. Make a hypothesis. The water level rose. The water level dropped. The water level stayed the same.
  22. 22. C. Scientific Method 3. Test your hypothesis. How could we test our hypothesis? 4. Analyze the results. What happened during our test? 5. Draw conclusions. Was our hypothesis correct? Is further testing necessary?
  23. 23. D. Experimental Design • Experiment - organized procedure for testing a hypothesis • Key Components: – Control - standard for comparison – Single variable - keep other factors constant – Repeated trials - for reliability
  24. 24. D. Experimental Design • Types of Variables – Independent Variable • The variable in the experiment that you control • adjusted by the experimenter • what you vary – Dependent Variable • the result of the independent variable • changes in response to the indep. variable • what you measure
  25. 25. D. Experimental Design • Hypothesis: Storing popcorn in the freezer makes it pop better. • Control: Popcorn stored at room temp.
  26. 26. D. Experimental Design • Single variable: Storage temperature • Constants: Popcorn brand Freshness Storage time Popper
  27. 27. D. Experimental Design • Independent Variable: Storage temperature • Dependent Variable: Number of unpopped kernels
  28. 28. Scientists are testing a new drug on 6 patients to see how it effects the growth of breast cancer. Identify how you would do control group, experimental group. Also, identify the independent and dependent variables.