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					Warm up
   Why would a scientist do an experiment?
   What is the difference between an
    observation and an inference?
   What is a variable?




                                              1
Warm up answers
   To answer a question
   Direct observation v. interpretation
   A variable is what can change in an
    experiment




                                           2
Experiment vocab
   Variable
   Independent variable
   Dependent variable
   Controlled variable(s)




                             3
Variable
   Aspects of an experiment that may change




                                               4
Independent variable
   Part of an experiment that the scientist
    manipulates to study the effects of the
    change




                                               5
Dependent variable
   Part of an experiment that the scientist is
    measuring.
   Any change to this variable is caused by the
    independent variable
   Unless there is a problem with the controlled
    variable(s)



                                                    6
Controlled variable (s)
   Part of an experiment that must stay the
    same for all trials




                                               7
Parts to an experiment
   Question
   Hypothesis
   Materials
   Procedure
   Data
   Conclusion
   Report

                         8
Today’s activities
   Read chapter 1 section 2
   Vocab on page 30
   Questions and answers on page 15




                                       9
                      Figure 1-8 Redi’s Experiment on
                      Spontaneous Generation
Section 1-2


   OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
   HYPOTHESIS: Flies produce maggots.
   PROCEDURE
                                 Uncovered jars                        Covered jars

   Controlled Variables:
   jars, type of meat,
   location, temperature,
   time                                                    Several
                                                           days pass
   Manipulated Variables:
   gauze covering that
   keeps flies away from
   meat
   Responding Variable:
   whether maggots
   appear               Maggots appear                              No maggots appear
   CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous
                    generation of maggots did not occur.




                                                                                                 10
                Figure 1-10 Spallanzani’s Experiment

Section 1-2




              Gravy is boiled.   Flask is   Gravy is teeming
                                 open.      with microorganisms.




              Gravy is boiled.   Flask is   Gravy is free of
                                 sealed.    microorganisms.

                                                                   11
                     Figure 1-11 Pasteur’s Experiment
       Section 1-2




Broth is boiled.     Broth is free of   Curved neck   Broth is
                     microorganisms     is removed.   teeming with
                     for a year.                      microorganisms.




                                                                 12
Cool down
   What is the difference between a hypothesis,
    a conclusion, and a theory?




                                               13

				
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