Uploaded by Monica Bhaskar

Designing a Controlled Experiment

Designing a Controlled Experiment
In experiments, to show the cause and effect relationship, scientists study factors called
a) Independent Variable: This is the experimental variable, the factor that is changed in the
experiment. The “CAUSE”
Designing a Controlled Experiment
a) Dependent Variable: This variable changes in response to the independent variable. This is
measured during an experiment; they are experimental data- the “EFFECT”
b) Control Factors: Also called constants these are conditions that remain the same during an
Designing a Controlled Experiment
In a Controlled experiment only ONE independent variable is tested at one time.
We setup 2 groups in a controlled experiment:
a) Control group: The control group is the part of the experiment that
 Does not receive the independent variable,
 Receives all the control factors
 Is used as the point of comparison
Designing a Controlled Experiment
b) Experimental Group: This group is the part that
receives the independent variable
receives the control factors
In the controlled experiment both the groups are treated exactly the same except the experimental
group gets the factor (independent variable) that you are testing.
Scientific Process
 What is a hypothesis?
A proposed answer to a scientific question
 What is a theory?
A proposed explanation for a wide range of observations and experimental results that is also
supported by a wide range of evidence
 Why are theories never proven?
Because new scientific evidence can lead to a theory being changed or discarded
Scientific process
 What is the difference between a theory and a hypothesis?
A theory explains a wide range of observations; a hypothesis is a proposed answer to one scientific
 How can you remember the difference between an independent variable and a dependent
Think about what the words independent and dependent mean.