experimental design & the scientific method
DESCRIPTION
Experimental Design & the Scientific Method. Physical Science 8 2013-2014. Variable. The condition or factor that CHANGES in an experiment so the effects can be observed. Dependent Variable (DV). A variable whose value DEPENDS on the value of another variable. - PowerPoint PPT PresentationTRANSCRIPT
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Experimental Design &the Scientific Method
Physical Science 82013-2014
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Variable
The condition or factor that CHANGES in an experiment so the effects can be observed.
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Dependent Variable (DV)A variable whose value DEPENDS on
the value of another variable.
To identify, ask: What is actually being measured in the experiment?
When graphing, usually goes on Y axis.
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Independent Variable (IV)A variable whose value does not depend
on the value of another variable.
To identify, ask: What is being changed to see an outcome in the experiment?
When graphing, usually goes on X axis.
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Control Group/ConstantsA condition or factor that is kept the
same throughout an experiment.
To identify, ask: Which group is receiving no “treatment”?
A proper experiment must have a control.
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Experimental GroupA condition or factor that is changed
or tested in an experiment.
To identify, ask: What is being changed to see an outcome in the experiment?
A proper experiment will only change ONE thing at a time!
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Qualitative Data
• Deals with descriptions.• Data can be observed but not measured.• Colors, textures, smells, tastes, appearance,
beauty, etc.• Qualitative → Quality
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Quantitative Data
• Deals with numbers.• Data which can be measured.• Length, height, area, volume, weight, speed, time,
temperature, humidity, sound levels, cost, members, ages, etc.
• Quantitative → Quantity
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The Scientific Method
Definition: An organized way to solve a problem.
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Step #1
State the Problem
Which means: What is the effect of _________ on _________?
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Step #2
Gather information
Which means: research (books, on the internet, journals, etc)
observations (using your 5 senses!)
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Step #3
Form a Hypothesis
Which means: Make an educated guess based on your research!
must be written in “If this…. then that” format
must be measurable
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Step #4
Perform Experiment
Which means: step by step procedure identify control and experimental group list materials needed
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Step #5
Record and Analyze Data
Which means: use data table, graphs and charts to organize
does the data make sense?
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Step #6
Reach a Conclusion
Which means: Always state whether your hypothesis was
correct. Explain why or why not, sources of error, and
what happened.
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An exampleA student wonders if it possible to float a cork in the middle of a glass of
water without touching it. He looks up the density of a cork and of water on the internet. He finds out that water has a higher density than the cork. He also looks in his science book to see if the experiment has been done before, but it hasn’t. From the information he gathers, he does think that a cork will float in the center of a glass of water. He puts the materials for his experiment (a plastic cup, a cork, a spoon, and water) together. He finds a flat surface and fills the cup with water and drops the cork in. He writes down on a sheet of paper his results. The cork does float in the water, but it goes to the side of the cup. He then blows on the cork and again, it goes only temporarily to the middle of the cup, but then goes back to the side. He writes that down. Finally, he adds one spoonful of water at a time until the water is almost coming over the top, but not spilling over. The cork floats in the middle and stays there! The student felt excited by his results.
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1. What is the problem?2. What information did the student gather
and where did he gather it from?3. What was his hypothesis? 4. What did the student do in his experiment?
(list the steps)5. What would his data table look like?6. What was his conclusion?
Cork Example