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Exploring the Experimental Method in Environmental Science

"Discover the steps of the experimental method in environmental science, from observation and hypothesizing to experimenting and analyzing data. Learn how scientists draw conclusions and communicate results effectively."

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Exploring the Experimental Method in Environmental Science

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  1. Chapter 2 Tools of Environmental Science Section 1: Scientific Methods Day one

  2. The Experimental Method – Scientific Method • Scientists make most of their discoveries using the experimental method. • This method consists of a series of steps that scientists worldwide use to identify and answer questions.

  3. Observing • Observation is the process of obtaining information by using your senses (what is different or changed?) • Observing is the first step of the experimental method. • Observations can take many forms, including descriptions, drawings, photographs, videos and measurements.

  4. Hypothesizing and Predicting • A hypothesis is a specific, testable prediction about what you expect to happen in an experiment that is based on observations • A hypothesis is not merely a guess like a prediction it relates how changing one variable effects another variable. • A good hypothesis should make logical sense and be testable If This happens… then this will happen… •A example of a hypothesis statement would be, As the (independent variable changes) then the (dependent variable) will (describe the effect)

  5. Hypothesizing and Predicting • Predictionis a guess of what you think will happen next in a certain situation • A prediction is used to test a hypothesis. • Predictions are guesses but don’t relate one variable to another variable

  6. Hypothesizing and Predicting • Ex of Prediction I think today the stock market prices are going to go up • Ex of a hypothesis. • As interest rates go lower then stock market prices go higher • 2 variables linked together that we can test them

  7. Hypothesizing and Predicting • It is important that any hypothesis can be disproved. • Every time a hypothesis is disproved, the number of possible explanations for an observation is reduced. • By eliminating possible explanations, a scientist can zero in on the best explanation.

  8. Experimenting • Experiment a procedure carried out under controlled conditions to test a hypothesis or possible solution to a problem • Experiments should be designed to pinpoint cause-and-effect relationships. • That is Changing one variable causes this effect in a second variable

  9. Experimenting • Good experiments have two essential characteristics: • Experimental group • Control group experimental hypothesis will always be phrased as a cause-and-effect statement. For example, researchers might propose a hypothesis that: Administration of Medicine A will resultin a reduction of symptoms of Disease B

  10. Experimenting • Experimental group is the group in the experiment that is identical to the control group except for one factor and is compared with controls group. (Gets the real medicine) • Control group is the group in the experiment that serves as a standard of comparison with another group to which the control group is identical except for one factor. (Gets sugar pill)

  11. Experimenting • Variable is the factor that changes in an experiment in order to test a hypothesis. (Sugar Pill vs Real Medicine) • To test for one variable, scientists usually study two groups or situations at one time, with the variable being the only difference between the two groups.

  12. Organizing and Analyzing Data • Dataany piece of information acquired through observation or experimentation. • Qualitative data- description • Quantitative data- numbers • Organizing data into tables and graphic illustrations helps scientists analyze the data and explain the data clearly to others. • Graphs are often used by scientists to display relationships between variables in the data.

  13. Organizing and Analyzing Data • Bar graphs are useful for comparing the data for several things in one graph.

  14. Organizing and Analyzing Data • Graphing the information makes the trends presented in tables easier to see. Table Bar graph

  15. Drawing Conclusions • Scientists determine the results of their experiment by analyzing their data and comparing the outcome of their experiments with the control group and their hypothesis. • Ideally, this comparison provides the scientist with an obvious conclusion does the data support the hypothesis or negate the hypothesis

  16. Drawing Conclusions • However, often the conclusion is not obvious. • In these cases, scientists often use mathematical tools to help them determine whether the differences are meaningful or are just a coincidence.

  17. Repeating Experiments • Scientists often repeat their experiments. • The more often an experiment can be repeated with the same results, in different places and by different people, the more confident scientists become about the reliability of their conclusions. • Scientists look for a large amount of supporting evidence before they accept a hypothesis.

  18. Communicating Results • Scientists publish their results, sometimes in scientific articles, to share what they have learned with other scientists. • Scientific articles include: • Question the scientist explored • Reasons why the question is important • Research related information • Procedures steps describing how experiment was done • Data collected • Analysis scientist’s interpretation of the data.

  19. The Correlation Method • When the use of experiments to answer questions is impossible or unethical, scientists test predictions by examining correlations. • Correlation is the linear dependence between two variables.

  20. The Correlation Method • An example is the relative width of a ring on a tree trunk is a good indicator of the amount of rainfall the tree received in a given year. • Correlation is Trees produce wide rings in rainy years and narrow rings in dry years.

  21. The Correlation Method • The scientists used tree ring width to determine past climate changes

  22. The Correlation Method • Although correlation studies are useful, they do not necessarily prove cause-and-effect relationships between two variables. • Scientists become more sure about their conclusions only if they find the same correlation in different places and as they continue to eliminate other possible explanations.

  23. Scientific Habits of Mind • Good scientists tend to share several key habits of mind, or ways of approaching and thinking about things. • The first habit of mind is curiosity. Good scientists are endlessly asking questions which drives them to observe and experiment. • The second habit of mind is skepticism. This means that good scientists do not believe everything that they are told.

  24. Scientific Habits of Mind • The third habit of mind is openness to new ideas. Good scientists keep an open mind to how the world works. • Another habit of mind is intellectual honesty. A good scientist is willing to recognize the results of an experiment even though it may mean that his or her hypothesis was wrong.

  25. Scientific Habits of Mind • Lastly, good scientists share imagination and creativity. • They are not only open to new ideas, but also able to conceive new ideas themselves. • They have the ability to see patterns or trends where others do not or can imagine things that others cannot. • This allows good scientists to expand the boundaries we know.

  26. ImaginationandCreativity • An example being when John Snow created a spot map which effectively pinpointed the source of a cholera epidemic in 1854.

  27. hypothesis – a testable explanation of a situation that can be supported or disproved through experimentation • variable – changeable factor; experiments only test ONE variable at a time • independent variable – the factor that is changed by the experimenter; I change the Independent variable (CAUSE) • dependent variable – the factor that is affected by changes in the independent variable; the dependent depends on the independent (EFFECT) • control- the group in an experiment that is not changed; used to show the results of an experiment are a result of the independent variable being changed

  28. Scientific Method - Controls and Variables

  29. Steps in the Scientific Method • Problem • Observation • Hypothesis • Experiment • Conclusion • Retest P O H E C

  30. Scientific Experiments Follow Rules. • An experimenter changes one factor and observes or measures what happens.

  31. The Control Variable • The experimenter makes a special effort to keep other factors constant so that they will not affect the outcome. • Those factors are called control variables.

  32. What is the Purpose of a Control? • Controls are NOT being tested • Controls are used for COMPARISON

  33. Other Variables • The factor that is changed is known as the independent variable. • The factor that is measured or observed is called the dependent variable.

  34. Example of Controls & Variables • For example, suppose you want to figure out the fastest route to walk home from school. You will try several different routes and time how long it takes you to get home by each one. • Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

  35. What are the Variables in Your Experiment? • Varying the route is the independent variable • The time it takes is the dependent variable • Keeping the same walker throughout makes the walker a control variable.

  36. One more thing… it is best to make several trials with each independent variable.

  37. Scientific Method Review • IBM thinks that a special juice will increase the productivity of workers. They create two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). • Group A is given the special juice to drink while they work. • Group B is not given the special juice. After an hour, The Examiner counts how many stacks of papers each group has made. • Group A made 1,587 stacks, special juice • Group B made 2,113 stacks. No juice

  38. IBM Answers • Identify the: • Control Group – • Independent Variable – • Dependent Variable – • What should IBM conclusion be? • How could this experiment be improved?

  39. IBM Answers • Identify the: • Control Group – Group B • Independent Variable – Special Juice • Dependent Variable – Stacks of Paper • What should IBM conclusion be? Juice doesn’t work • How could this experiment be improved? Control the amount of juice they drink (dosage)

  40. YouTube! Scientific Method Song

  41. Ecolog

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