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EXPERIMENTAL DESIGN
                   SCIENTIFIC METHOD

      Dr. Sanaa Abd Eltawab 1 & Dr. Rasha Aly Elsayed 2
      1
        Beni Suef University 2 Al Azhar University




3rd Lecture
Intended learning outcomes
2


       How Scientists Work: Solving the Problems
       Definition of Scientific Method
       Overview & Listing the Scientific Method Steps
       Scientific Method Example
            - Observing     - Questioning
            - Researching        - Hypothesizing
            - Experimentation    - Collect and record data
            - Analyzing data      - Draw conclusions
            - Determine limitations
            - Publish results
            - Repeat Experiment
How Scientists Work: Solving the Problems
3

       Much of biology deals with solving problems
       These problems can be environmental,
        ecological, health related, etc.
       No matter what types of problems
        are being studied, scientists use
        the same problem-solving steps
        called the Scientific Method

       The scientific method, is the most powerful
        tool yet devised for the analysis and
        solution of problems in the natural world.
Scientific Method: Definition
4


     Scientific method is a body of
    techniques      for     investigating
    phenomena and acquiring new
    knowledge, as well as for
    correcting and integrating previous
    knowledge. It is based on
    gathering observable, empirical
    and measurable evidence subject
    to specific principles of reasoning,
    the collection of data through
    observation and experimentation,
    and the formulation and testing of
    hypotheses.
Scientific Method: Listing the Steps
5



       Make an Observation
       Define the Problem
       Research the Problem
       State the Hypothesis
       Experiment to test Hypothesis
       Collect and Record Data
       Analyze Data
       Draw Conclusions
       Determine Limitations
       Report Results
                                    If needed, Do more investigation
First                  What does the scientist want
                          Question        to learn more about?

                          Then
6
                         Research        Gathering of information


                          Next

    S       O                           An “Educated” guess of an
                        Hypothesis
    C
                                         answer to the question


        M   V             Then
    I
            E
                                          Written and carefully

        E
                        Procedure/        followed step-by-step
                          Method       experiment designed to test
                                              the hypothesis


    E   T   R             Next



    N   H   V                Data
                                       Information collected during
                                             the experiment



        O   I             And                    And


    T
                                       Written description of what

            E           Observations     was noticed during the


    I
        D                                      experiment



            W
                         Finally


    F                    Conclusion
                                       Was the hypothesis correct
                                             or incorrect?

    I
Scientific Method
                                  Ask Question
7

                                 Do Background
                                   Research


                                   Construct                   Think!
Let’s break each                   Hypothesis                 Try Again

 of these steps                    Test with an
 down into their                   Experiment

   individual                    Analyze Results
  components:                    Draw Conclusion


                                            Hypothesis is False
                    Hypothesis is True
                                             or Partially True


                                 Report Results
Example for Scientific Method
8


   Example: the Scientific Method using Redi’s
    Experiment on Spontaneous Generation
   He was trying to disprove the idea of spontaneous
    Generation (or actually that flies came from
    maggots, which came from flies)
1. Observing
9


       Make an observation
           See something unusual



   Redi wanted to show
    what caused the
    appearance of maggots
    (and then flies) on meat
2. Questioning
10


        Recognize, state or define the problem
        Must be in the form of a question
        The obvious question is:
            What’s the source of these worms?
Belief based on prior
11
             observations


  Redi observed that maggots appeared on
   meat a few days after flies were on meat
  No microscope = no way to see eggs

  But Redi believed that maggots came from

   eggs that were laid by flies
12
3.
13
                     Researching
        Gather information related to the
         problem

            Read, observe, measure, take
             samples, etc.
4. Hypothesizing
14




        A hypothesis is:
            An educated guess, trial answer, possible
             solution, prediction
            Must be a statement
            Must be testable or measurable
            Is based on your research and previous
             experience
Forming a Hypothesis
15

Predict a possible answer to the problem or question.

              Redi’s Hypothesis:
             Flies produce maggots.
        How could he test this?
            Through a controlled experiment
5-Redi’s Controlled Experiment
16


        Redi used two groups of jars
            Jars that contained meat and no cover
            Jars that contained meat and gauze cover

                           Jars with meat

                             Uncovered
                             jars
                             Covered
                             jars
Control and Experimental Groups
17



     
         Control group: used as a standard of
         comparison
        Experimental group: the group containing the
         factor (variable) that has been changed
      (manipulated or independent variable)
                          Two groups
                            of jars
                         Uncovered
                         jars
                             Covered
                             jars
Variables in an Experiment
18


        Variables - Factors that can be changed
                                 Variables


Controlled Variables         Manipulated Variable –         Responding Variable-
- all the variables that   (also called the
remain constant            Independent Variable) -         (also called the
                           factor in an experiment that    Dependent Variable) - the
                           a scientist purposely          outcome or results, factor in
                           changes                        an experiment that may
                                                          change because of the
                                                          manipulated variable


     what a scientist wants to observe
Setting up a Controlled Experiment
19


        In a controlled experiment,
         only one factor is changed at a
         time.
            Independent variable: the
             factor that is deliberately
             changed
            Dependent variable:
              the factor that the scientist wants
             to observe; it changes in
             response to the independent
             variable
Variables in Redi’s Experiment
20




         Controlled Variables: jars, type of meat,
          location, temperature, time
         Manipulated Variables:
          gauze covering
          that keeps flies
          away from meat
Let’s think about this.…
21




     Which is the control group?        Uncovered jars

     Which is the experimental group?
                                        Covered jars

                    Two groups of
                    Jars with meat
                     Uncovered
                     jars
                        Covered
                        jars
Redi’s Experiment on Spontaneous Generation

     OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
     HYPOTHESIS: Flies produce maggots.
22
     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.
6. Collect and Record Data
23
20


 Data: observations and measurements
               made in an experiment
           Types of Recorded Data
        Quantitative - observations that
         involve measurements/numbers;
         i.e. 3 days, 12 maggots, 4 g, 13 sec,
         8 liters
        Qualitative - observations that
         do not involve numbers, are of a
         descriptive nature
         i.e. white maggots covered the meat,
         leaves were all wilting
7. Analyze the Data
24
21



        Examine data tables, charts, and graphs
        Examine experimental notes
        Look for trends, patterns, and averages
        What does the data show
        Put your data into words
8. Draw Conclusions
25

        Restate the hypothesis:
              Example: Flies produce maggots.
        Accept or reject the hypothesis.
        Support your conclusion with specific, numerical data.
        What was Redi’s conclusion?
          Flies lay eggs too small to be seen.
          Maggots found on rotting meat are produced
           from the eggs laid by flies.
          Maggots are not appearing due to
           spontaneous
           generation!
9. Determine Limitations
26




        Scientists look for possible
         flaws in their research.
        They look for faulty
         (inaccurate) data.
        They look for experimental
         error or bias's.
        They decide on the validity
         of their results.
        They make suggestions for improvement or raise
         new questions.
10. Publish Results
27

         Communication is an
          essential part of science
                            Scientists report their
                             results in journals,
                             on the internet, or
                             at conferences
                            This allows their
                             experiments to be
                             evaluated and repeated
                            Scientists can build on previous
       Redi’s experiment
     on insects generation
                             work of other scientists
Repeating the Investigation
28



        Sometimes results are unexpected.
                 Repeat the experiment!
            John Needham challenged Redi’s experiment and
             designed his own to show that spontaneous
             generation CAN occur under certain
             circumstances.
            Lazzaro Spallanzini
             designed a slightly
             different experiment
             to improve on
             Needham’s work
Repeating the Experiment
                         (continued)
29



        Louis Pasteur further modified the
         experiment.
Thank You
30

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Scientific method

  • 1. EXPERIMENTAL DESIGN SCIENTIFIC METHOD Dr. Sanaa Abd Eltawab 1 & Dr. Rasha Aly Elsayed 2 1 Beni Suef University 2 Al Azhar University 3rd Lecture
  • 2. Intended learning outcomes 2  How Scientists Work: Solving the Problems  Definition of Scientific Method  Overview & Listing the Scientific Method Steps  Scientific Method Example - Observing - Questioning - Researching - Hypothesizing - Experimentation - Collect and record data - Analyzing data - Draw conclusions - Determine limitations - Publish results - Repeat Experiment
  • 3. How Scientists Work: Solving the Problems 3  Much of biology deals with solving problems  These problems can be environmental, ecological, health related, etc.  No matter what types of problems are being studied, scientists use the same problem-solving steps called the Scientific Method  The scientific method, is the most powerful tool yet devised for the analysis and solution of problems in the natural world.
  • 4. Scientific Method: Definition 4 Scientific method is a body of techniques for investigating phenomena and acquiring new knowledge, as well as for correcting and integrating previous knowledge. It is based on gathering observable, empirical and measurable evidence subject to specific principles of reasoning, the collection of data through observation and experimentation, and the formulation and testing of hypotheses.
  • 5. Scientific Method: Listing the Steps 5  Make an Observation  Define the Problem  Research the Problem  State the Hypothesis  Experiment to test Hypothesis  Collect and Record Data  Analyze Data  Draw Conclusions  Determine Limitations  Report Results If needed, Do more investigation
  • 6. First What does the scientist want Question to learn more about? Then 6 Research Gathering of information Next S O An “Educated” guess of an Hypothesis C answer to the question M V Then I E Written and carefully E Procedure/ followed step-by-step Method experiment designed to test the hypothesis E T R Next N H V Data Information collected during the experiment O I And And T Written description of what E Observations was noticed during the I D experiment W Finally F Conclusion Was the hypothesis correct or incorrect? I
  • 7. Scientific Method Ask Question 7 Do Background Research Construct Think! Let’s break each Hypothesis Try Again of these steps Test with an down into their Experiment individual Analyze Results components: Draw Conclusion Hypothesis is False Hypothesis is True or Partially True Report Results
  • 8. Example for Scientific Method 8  Example: the Scientific Method using Redi’s Experiment on Spontaneous Generation  He was trying to disprove the idea of spontaneous Generation (or actually that flies came from maggots, which came from flies)
  • 9. 1. Observing 9  Make an observation  See something unusual  Redi wanted to show what caused the appearance of maggots (and then flies) on meat
  • 10. 2. Questioning 10  Recognize, state or define the problem  Must be in the form of a question  The obvious question is:  What’s the source of these worms?
  • 11. Belief based on prior 11 observations  Redi observed that maggots appeared on meat a few days after flies were on meat  No microscope = no way to see eggs  But Redi believed that maggots came from eggs that were laid by flies
  • 12. 12
  • 13. 3. 13 Researching  Gather information related to the problem  Read, observe, measure, take samples, etc.
  • 14. 4. Hypothesizing 14  A hypothesis is:  An educated guess, trial answer, possible solution, prediction  Must be a statement  Must be testable or measurable  Is based on your research and previous experience
  • 15. Forming a Hypothesis 15 Predict a possible answer to the problem or question. Redi’s Hypothesis: Flies produce maggots.  How could he test this?  Through a controlled experiment
  • 16. 5-Redi’s Controlled Experiment 16  Redi used two groups of jars  Jars that contained meat and no cover  Jars that contained meat and gauze cover Jars with meat Uncovered jars Covered jars
  • 17. Control and Experimental Groups 17  Control group: used as a standard of comparison  Experimental group: the group containing the factor (variable) that has been changed (manipulated or independent variable) Two groups of jars Uncovered jars Covered jars
  • 18. Variables in an Experiment 18  Variables - Factors that can be changed Variables Controlled Variables Manipulated Variable – Responding Variable- - all the variables that (also called the remain constant Independent Variable) - (also called the factor in an experiment that Dependent Variable) - the a scientist purposely outcome or results, factor in changes an experiment that may change because of the manipulated variable what a scientist wants to observe
  • 19. Setting up a Controlled Experiment 19  In a controlled experiment, only one factor is changed at a time.  Independent variable: the factor that is deliberately changed  Dependent variable: the factor that the scientist wants to observe; it changes in response to the independent variable
  • 20. Variables in Redi’s Experiment 20  Controlled Variables: jars, type of meat, location, temperature, time  Manipulated Variables: gauze covering that keeps flies away from meat
  • 21. Let’s think about this.… 21 Which is the control group? Uncovered jars Which is the experimental group? Covered jars Two groups of Jars with meat Uncovered jars Covered jars
  • 22. Redi’s Experiment on Spontaneous Generation OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. 22 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.
  • 23. 6. Collect and Record Data 23 20 Data: observations and measurements made in an experiment Types of Recorded Data  Quantitative - observations that involve measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters  Qualitative - observations that do not involve numbers, are of a descriptive nature i.e. white maggots covered the meat, leaves were all wilting
  • 24. 7. Analyze the Data 24 21  Examine data tables, charts, and graphs  Examine experimental notes  Look for trends, patterns, and averages  What does the data show  Put your data into words
  • 25. 8. Draw Conclusions 25  Restate the hypothesis: Example: Flies produce maggots.  Accept or reject the hypothesis.  Support your conclusion with specific, numerical data.  What was Redi’s conclusion?  Flies lay eggs too small to be seen.  Maggots found on rotting meat are produced from the eggs laid by flies.  Maggots are not appearing due to spontaneous generation!
  • 26. 9. Determine Limitations 26  Scientists look for possible flaws in their research.  They look for faulty (inaccurate) data.  They look for experimental error or bias's.  They decide on the validity of their results.  They make suggestions for improvement or raise new questions.
  • 27. 10. Publish Results 27  Communication is an essential part of science  Scientists report their results in journals, on the internet, or at conferences  This allows their experiments to be evaluated and repeated  Scientists can build on previous Redi’s experiment on insects generation work of other scientists
  • 28. Repeating the Investigation 28  Sometimes results are unexpected. Repeat the experiment!  John Needham challenged Redi’s experiment and designed his own to show that spontaneous generation CAN occur under certain circumstances.  Lazzaro Spallanzini designed a slightly different experiment to improve on Needham’s work
  • 29. Repeating the Experiment (continued) 29  Louis Pasteur further modified the experiment.