Introduction to Science
What is the purpose of science?
• Science is the process of
trying to understand the
world around us
• Questioning
• Observations
• Curiosity
• Logical thinking
• Examining evidence
Empirical Evidence
• Evidence that is
observed directly
through research and
investigation
• Used to construct testable
explanations and predictions of
natural events
• May support or overturn long
standing ideas
Observations
• Using our senses and other
tools to study the world
around us
• Used to gather empirical
evidence
• For example, how do you
know if you have allergies?
• Experiment and observe
Data
• Observations are often
recorded as data and can be
analyzed
• Qualitative Data
• Descriptions of observations such as
sight, sound, smell, taste
• Quantitative Data
• Data that can be measured or
counted
• Mass, volume, temperature
Hypothesis
• Scientists use observations, data and
scientific literature to form a
hypothesis
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•
•
•
Proposed answer for a scientific question
Must be specific and testable
Educated guess
Leads to a testable prediction of what happens if
the hypothesis is correct
• “ If…then….”
• If your hypothesis is untrue on the 1st attempt,
check for errors or bias
Using Experiments to Test a Hypothesis
• Experiments study variables to find
cause-and-effect relationships.
• Independent variables
• Dependent variables
• Experimental studies allow scientists
to determine what causes a
phenomenon
• Experiments should be repeated a
minimum of 3 times.
Independent Variable
• A condition that is being manipulated, or
changed, by the scientist
• Whatever changes you make affects the
results of the experiment
• Example: What type of soil will make the
farmer’s plants grow faster?
Dependent Variable
• Dependent variables are observed
and measured during the experiment
• Respond to the changes you made to
the independent variable
• Example: Because of the change in
soil the farmer made, his plants have
grown more quickly than in previous
years.
Graphing Variables
Blood Pressure Medication
Dependent Variable – Blood Pressure
A scientist is testing
medications to treat
high blood pressure.
The dose of the
medication is being
changed (manipulated)
and as a result, blood
pressure drops for 2 of
the medications.
Medicine A
Medicine B
Medicine C
Independent Variable
Dose 10mg
Dose 50mg
Dose 100mg
DRY MIX
Dependent Variable
Responding
Y axis
Manipulated
Independent Variable
X axis
Constant
• The conditions that do not change in an experiment
– they remain constant (the same).
• You should only test one variable at a time and other variables
should remain constant.
• What are we keeping constant in this experiment?
What is the one variable that we are testing?
• Example: Does the # of jumping jacks a person does
affect their heart rate?
• IV: # of jumping jacks
• DV: Heart rate
• Constants: No jumping jacks, same weight range, same
age, etc.
Control Group
• A control group is a standard by which the
test results can be compared.
• You need something to compare your
experiment results to
• Which one is the experimental group and
which one is the control group?
• Example: Does chewing gum affect how high
a student scores on a test?
• Experimental group: Gum
• Control group: No gum
Theory
• Theories explain a wide range of
observations and experimental results
• A theory is supported by scientific evidence
• An experiment was repeated over and over
and over and the same results were found
every time
• A theory can be changed based on new
evidence
• New information
• New technology
Big Bang Theory
Lab Reports
• The scientific method is
the process for
communicating your
experimental results.
• Written in an outline form
• Includes observations, collected
data and drawings
• The experiment could be
repeatable
1.
2.
3.
4.
State the Problem
Form a testable hypothesis
List materials needed
List the experimental
procedure
5. Analyze your results
6. Form a valid conclusion: Was
your hypothesis correct?
Why or why not?