Identifying Variables - PowerPoint

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					             Scientific Inquiry
 Observing & Questioning (How,
  What, Why, Which?)
 Background Research (internet,
  books)
 Experiment Design
     What could I measure?
     What could I change that may affect
      what I observe?
     What will I not change?
   Construct a Hypothesis
     If......then.... because statement
                                            1
Types of Variables


A variable is something that is changed
A constant, or control, is something that does not
  change




There are 3 main types of variables…

                                                     2
3 Types of Variables
   INDEPENDENT VARIABLE

   DEPENDENT VARIABLE

   CONTROL




                           3
INDEPENDENT VARIABLE
 Independent     Variable: The variable
    that is changed by the scientist; the ‘I
    control’ variable

   What you change in the experiment
     The amount of liquid


     The type of liquid


     The colour of light to grow a plant
                                               4
DEPENDENT VARIABLE
 Dependent  Variable: The variable that
 might change because of what the
 scientist changes – what is being
 measured

  The time to absorb the liquid
  The amount of the expansion
  How tall the plant grows



                                           5
CONTROL
 Control:  The variable that we keep
    constant – this should not change

   Things the scientist wants to control in
    an experiment to make sure it is fair test

     The amount of time we stirred the liquid
     The same type of beaker is being used
     Water is poured in the same way

                                                 6
Control Variable


Control: The variable that we keep constant –
  this should not change




                                                7
Your hypothesis can TELL you
what your variables are!

Ex. If I drink Mountain Dew before bed, then
  I will not sleep very much.

Ind. Variable: Drinking Mountain Dew
Dep. Variable: the amount of sleep
Con. Variable: same bed, same bed time,
  same pajamas
                                               8
Practice
 Use this hypothesis to identify the variables:

If I leave all the lights on all day,
    then my electric bill will be expensive

Ind. Variable: ______________________
Dep. Variable: ______________________
Con. Variable: ______________________


                                                  9
        Problem          Independent Dependent   Control
                           Variable   Variable   Variable
     How does
     coloured light
     affect the growth
     of plants?

     How does
     exercise affect
     the production of
     carbon dioxide?

     Which laundry
     detergent
     removes stains
     the best?

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