# 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
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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…

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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

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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: ______________________

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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?

10

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