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How Scientist Think Scientist use reasoning when examining the world. Deductive reasoning is the process of using general priciples to explain individual observations. Inductive reasoning is the process of using specific observation to formulate general principles The Scientific Process Joseph Farman, who first reported the ozone hole, is practicing science, and what he was doing in Antartica was science. Science is a particular way of investigating the world, of forming general rules about why things happen by observing particular situation. Scientis like Farman is an observer, some one who looks at the world in order to understand how it works. How Science Is Done Doing Observation and writing observation result, Make a Question or a problem Construct a hypotesis Hypotesis is a proposition that might be true Making Prediction Testing a hypothesis with an experiment Looking for experiment and writing experiment result Forming conclusion Observation Gap between hope and fact The key to any succesful scientific investigation is careful observation Farman and other scientists had studied the skies over the Antartic for many years, noting a thousand details about temperatur, ligt, and levels of chemicals. Had these scientist not kept careful records of what they observed. Farman might not have noticed that ozone levels were dropping. Hypothesis Is a guess that might be true What the scientist guessed was that chlorine from CFCs release into the atmosphere was reacting chemically with ozone over the Antartic, converting ozone into oxygen gas and onazen and in the process removing the ozone shield from our earths atmosphere. Often, scientis will form alternative hypotesis if they have more than one guess about what thyey observe Prediction If the CFCs hypothesis is correct, then several consequences can reasonable be expected We call these expected consequences predictions. A prediction is what you expect to happen if hypothesis is true The CFCs hypothesis predicts that if CFCs are responsible for producing ozone hole. Testing Scientist set out to test the CFC hypothesis by attempting to verify some of its prediction. To test the hypothesis, atmospheric samples ere collected from the atmospheric samples were collected from the atmosphere over 6 miles up a high altitude ballon. Analysis of the samples revealed CFCs, as predicted. Were the CFCs interacting with the ozone? The samples contained free chlorine and fluorine, confirming the breakdown of CFC molecules. The result of the experient thus support the hypothesis Control Variable: each factor that might influence by many factors To evaluate alternative hypothesis about one variable, all the other variables must be kept constant so that we do not get misled or confused by these other influences This is done by carrying out two experiment in parallel: - The first experimental test: we alter one variable is known way to test a particular hypothesis - The second, called the control experiment, we do not alter that variable Conclution A hypothesis that has been tested and not rejected is tentatively accepted The hypothesis that CFCs released into the atmosphere ae destroying the earth's protective ozon shields is now supported by a great deal of experimenttal evidence and is widely accepted. A collection of related hypotheses that have been tested many times and not rejected is called theory.