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							      The Scientific Method
• What is the scientific method?
  – An approach for determining
    scientific rules and relationships
• Why do we need it?
  – It’s more convenient than just hoping
    you stumble over the rules and
    relationships
    The Scientific Method
•   Problem or question
•   Hypothesis
•   Design and conduct an experiment
•   Analyze results
•   Draw a conclusion

These steps form the basis for our lab
 reports!
      Step 1: The Question

• Ask the right question!
• Sometimes you need to make
  observations to come up with a
  question
       Step 2: Hypothesis
• How are variables related?
• Needs to be testable
• Needs to be consistent with the
  question
         Step 3: Experiment
• Make sure the experiment addresses the
  question and hypothesis
• Determine:
  – Constants: what doesn’t change
  – Independent variables: what you directly change
    (in Physics, we use Time a lot)
  – Dependent variables: what will change
    automatically when you change something else–
    what you observe
• Outline what you will do
• Do it!
  Step 3: Experiment (Cont’d)
• Make sure you control everything you
  can control
• Do many trials (at least 3)!
• Set up a table to accept your data
                         Data Tables
• Data tables are created when
  you design the experiment
• Then filled in when you        Time for ball to drop (s)
  perform the experiment
• When you see the data later,
  you should be able to            Trial Light Heavy
  immediately understand what            Ball  Ball
  the data meant
• Key aspects:                     1     0.54   0.40
   –   Title (with DV)
   –   Units                       2     0.32   0.51
   –   IV                          3     0.44   0.41
   –   Trials
   –   Averages                    Ave   0.43   0.44
                  Data Tables
                            Light Ball              Heavy Ball
• Lots of different ways    Trial   Time of         Trial    Time of
                                    flight (s)               flight (s)
  to make tables            1                       1
• Easiest solution (but     2                       2
  not very elegant) is to   3                       3
  make lots of small        Ave                     Ave
  tables
                                        Time of flight (s)
• More efficient is to              Trial   Light   Heavy
  combine tables                            Ball    Ball
                                    1
                                    2
                                    3
                                    Ave
 How to tell if your table is good
• If you looked at it 2 weeks
  after the experiment, could
  you immediately figure out    Time for ball to drop (s)
  what the numbers meant?
                                  Trial Light Heavy
• What was I measuring?                 Ball  Ball
• What units did I use?
• What’s different between        1     0.54   0.40
  this number and the one         2     0.32   0.51
  next to it?
                                  3     0.44   0.41
                                  Ave   0.43   0.44
    Step 4: Analyze Results
• What happened?
• Draw graphs (if necessary) to
  determine relationships
• Do whatever you need to do to
  draw a conclusion
       Step 5: Conclusion
• What did you learn about the
  hypothesis from the experiment?
• If it didn’t directly confirm (or
  refute) the hypothesis, what else
  needs to be done?
• What did we learn?
• What would you do differently next
  time?
         Keys to Success
• Consistency
 – Make sure the experiment and
   conclusion directly address the
   hypothesis and the problem
• Understanding
 – At the end, you need to clearly state
   what was learned
 – So be sure you learn something!