Control

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Control Variable Notes
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Where do I start?

• After you have a question that you want to answer
  using the scientific method, there are a few
  important things you need to think about while
  setting up your experiment.

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Example Question 1

• Does heating a cup of water allow it to dissolve
  sugar faster?

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THE CONTROL

• A control is the part of the experiment that
  remains the same.
• It may also be called the constant.

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How to Remember

• WHAT I KEEP THE SAME

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Back to the Example

• Question 1 Does heating a cup of water allow
  it to dissolve sugar faster?
• Control 1 Type of water, Type of sugar, amount
  of water

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CONTROL GROUP

• The control group provides a baseline for
  comparison.

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HOW TO REMEMBER

• LEAVE OUT WHAT YOU ARE TESTING

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Back to the Example

• Question 1 Does heating a cup of water allow
  it to dissolve sugar faster?
• Control 1 Type of water, Type of sugar, amount
  of water
• Control Group 1 Room temperature water

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What is a Variable?

• A variable is the part of the experiment that
  changes. An experiment usually has two kinds of
  variables independent and dependent.

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INDEPENDENT VARIABLE

• The variable that is changed by the scientist.
• To insure a fair test, a good experiment has only
  ONE independent variable. As the scientist
  changes the independent variable, he or she
  observes what happens.

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HOW TO REMEMBER

• WHAT I CHANGE

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Back to the Example

• Question 1 Does heating a cup of water allow
  it to dissolve sugar faster?
• Control 1 Type of water, Type of sugar, amount
  of water
• Control Group 1 Room temperature water
• I.V. 1 Temperature of the water

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DEPENDENT VARIABLE

• The variable that is caused by the change the
  scientist made.
• The scientist focuses his or her observations on
  the dependent variable to see how it responds to
  the change made to the independent variable.

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HOW TO REMEMBER

• WHAT I OBSERVE

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Back to the Example

• Question 1 Does heating a cup of water allow
  it to dissolve sugar faster?
• Control 1 Type of water, Type of sugar, amount
  of water
• Control Group 1 Room temperature water
• I.V. 1 Temperature of the water
• D.V. 1 How fast sugar dissolves

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Example 2

• Question 2 Does fertilizer make a plant grow
  bigger?

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Example 2

• Control(s)
• size of plant
• size of pot
• amount of soil
• type of soil
• amount of water

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Example 2

• Control Group
• A plant with no fertilizer

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Example 2

• Independent Variable (What I Change)
• Amount of fertilizer

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Example 2

• Dependent Variable (What I Observe)
• Height of plant

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Example 3

• Question 3 What type of dish soap best removes
  spaghetti sauce stains from plates?

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Example 3

• Control(s)
• amount of sauce
• type of plate
• amount of dish soap

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Example 3

• Control Group
• Using just water to wash

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Example 3

• Independent Variable (What I Change)
• type of dish soap

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Example 3

• Dependent Variable (What I Observe)
• Amount of sauce stain leftover.