Scientific Method and
Experimental Design
7th Grade Science
What is the Scientific
Method?
• It is a simple method scientists (and
non-scientists) use to conduct an
investigation
• It is a way to ask & answer scientific
questions by asking
questions & conducting
experiments
• You use it each day
when you make simple
choices
Inductive vs Deductive
Reasoning
• When using the scientific method to
explain data or develop theories,
scientists can use inductive or
deductive reasoning
– Inductive reasoning: uses evidence
and observations to make conclusions
– Deductive reasoning: uses beliefs and
what you know to make conclusions
(may try to find a way to make their
prior knowledge align with what they
were seeing)
Steps of Scientific Method
• Question/Problem
– Does (or will) _____ affect ______?
• Must relate to an observation
• Usually a “what”, “why”, or “how”
– Must be measureable
– Can lead to several types of
investigations
Steps of Scientific Method
• Hypothesis
– Statement that proposes (predicts) an
answer to the question based on
observation and data/research
– Focus on one variable only
(independent)
– Rules for writing hypothesis
• If _______ changes, then _______
changes.
• Must be testable, measurable,
and repeatable
Steps of Scientific Method
• Experiment
– Testing your hypothesis
(independent variable)
– Investigating to see if your
independent variable has an affect
on the dependent variable
• Collect data
– Must have numerous re-tests or trials (at
least 10) to support your results
– Measurements must be recorded with units
– Data can be qualitative (description based) or
quantitative (numbers based)
Steps of Scientific Method
• Conclusion
– Summary of your experiment that re-states
the hypothesis and explains why hypothesis
is supported or not supported
– Use data from experiment to draw conclusion
– Addresses possible errors
– Explains why experiment is important
Experimental Components
• Variables
– Independent
• What is tested
• Manipulated or changed in the experiment
– Dependent
• What is measured
• Changes due to the IV’s manipulation
(change)
– Does the (IV) affect the (DV)?
Experimental Components
• Constants
– All other variables that must remain the
same
– Ensures that you are only testing
the independent variable
• Control Group
– Group that has nothing done to it
(group without the IV)
– May not always have a control group
 non-defined, true comparison
Grade Level
Expectations (GLEs)
• 6th, 7th, and 8th
– 7.1.A.a (DOK 2), 7.1.A.b (DOK 2),
7.1.A.e (DOK 2)