Experimental Design and the Scientific Method Life Savers Lab.
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Transcript of Experimental Design and the Scientific Method Life Savers Lab.
Experimental DesignExperimental Designand the Scientific and the Scientific
MethodMethod
Life Savers LabLife Savers Lab
There isThere is NO SINGLE METHODNO SINGLE METHOD for doing science!!!!for doing science!!!!
However, science involves a series of However, science involves a series of common steps...common steps...
Steps of the Scientific MethodSteps of the Scientific Method
1. Make an 1. Make an ObservationObservation
Example:Example: • It takes students differing amounts of It takes students differing amounts of
times to eat a Life Savers.times to eat a Life Savers.
Steps of the Scientific MethodSteps of the Scientific Method
2. Ask a 2. Ask a QuestionQuestion
Examples:Examples:• Does flavor influence how long it Does flavor influence how long it
takes to eat a Life Savers?takes to eat a Life Savers?
• Does gender affect how long it Does gender affect how long it takes to eat a Life Savers?takes to eat a Life Savers?
Steps of the Scientific MethodSteps of the Scientific Method3. Form a 3. Form a HypothesisHypothesis and … and …
4. Make a 4. Make a PredictionPrediction HypothesisHypothesis:: A proposed explanation A proposed explanation
that answers your question.that answers your question.• This must be TESTABLE!This must be TESTABLE!• Statement: If_________, then_______Statement: If_________, then_______
PredictionPrediction:: A statement that A statement that forecasts what would happen if your forecasts what would happen if your hypothesis is true.hypothesis is true.
Steps of the Scientific MethodSteps of the Scientific Method
5. 5. TestTest your hypothesis your hypothesis
ExperimentExperiment:: An investigation that An investigation that tests your hypothesis under tests your hypothesis under controlled conditions. controlled conditions.
Experimental DesignExperimental Design: How you : How you set up your experiment. set up your experiment.
Experimental DesignExperimental Design Control GroupControl Group = = you use the you use the
control group data to compare to control group data to compare to your experimental group datayour experimental group data
Experimental GroupExperimental Group = the group = the group that is being tested onthat is being tested on
Experimental Design Cont.Experimental Design Cont. ConstantConstant = = Anything that stays the same during Anything that stays the same during
an experiment (ex: same flavor, same stop an experiment (ex: same flavor, same stop watch, etc)watch, etc)• Controlling your experiment ensures that Controlling your experiment ensures that extra extra
independent variables independent variables can’tcan’t sneak in and affect your sneak in and affect your datadata
Independent VariableIndependent Variable = = It It affectsaffects the the dependent variable. This is the variable that you dependent variable. This is the variable that you changechange. . • Ex: Color of lifesaver, Flavor of lifesaverEx: Color of lifesaver, Flavor of lifesaver
Dependent VariableDependent Variable = = It It dependsdepends on the on the independent variable. This is the variable you independent variable. This is the variable you measuremeasure. . • Ex: the length of time to consume a lifesaverEx: the length of time to consume a lifesaver
Experimental Design Cont.Experimental Design Cont. Let’s say you have 2 variables and you can’t tell which should be the Let’s say you have 2 variables and you can’t tell which should be the
dependent variable dependent variable and which should be the and which should be the independent variable independent variable
We know that the dependent variable depends on the independent We know that the dependent variable depends on the independent variablevariable
Put the variables into this sentence and see if it makes sense Put the variables into this sentence and see if it makes sense “______ “______ depends on ______”depends on ______”
Which sentence makes more sense?Which sentence makes more sense?
““TemperatureTemperature depends on the depends on the Number of SharksNumber of Sharks.”.”
““The The Number of SharksNumber of Sharks depends on depends on TemperatureTemperature.”.”
Temperature (C)Number of Sharks
15 22
18 18
20 16
Steps of the Scientific MethodSteps of the Scientific Method6. 6. Analyze DataAnalyze Data and and Draw ConclusionsDraw Conclusions Qualitative DataQualitative Data = = Deals with Deals with
descriptions. Observed, but not descriptions. Observed, but not measured.measured.• Ex: color changes to the lifesaver as you Ex: color changes to the lifesaver as you
consume itconsume it Quantitative DataQuantitative Data = =Deals with Deals with
numbers, can be measured numbers, can be measured • Ex: The number of seconds needed to Ex: The number of seconds needed to
consume a lifesaversconsume a lifesavers Hint: Think “N” for NUMBER!Hint: Think “N” for NUMBER!
The table surface is smoothThe table surface is smoothQualitativeQualitative
The peanut weighs 1.75 gThe peanut weighs 1.75 gQuantitativeQuantitative
The leaf is dark brownThe leaf is dark brownQualitativeQualitative
There are 15 flowers with white petals on themThere are 15 flowers with white petals on themQuantitativeQuantitative
Qualitative or Quantitative?Qualitative or Quantitative?(pay attention but you don’t have to write this down)(pay attention but you don’t have to write this down)
Graphing GuideGraphing GuideSome rules to follow….Some rules to follow….
Graphs are an easy way to display your Graphs are an easy way to display your data.data.
Which graph you use depends on what Which graph you use depends on what data you have.data you have.
Bar Graph Pie Graph Line Graph
(Comparing trends & changes)
(Comparing parts of a whole)
(Comparing groups)
Graphing Guide Cont.Graphing Guide Cont. Always remember to title your graph.Always remember to title your graph. Independent Variable always goes on X-axis Independent Variable always goes on X-axis
(horizontal).(horizontal). Dependent Variable always goes on Y-axis Dependent Variable always goes on Y-axis
(vertical).(vertical). Label the X and Y axis.Label the X and Y axis. When graphing, use the “When graphing, use the “Dry-Dry-MixMix” to help you ” to help you
remember. remember. DDependent – ependent – RResponding –esponding –YY axis ----- axis ----- MManipulated – anipulated – IIndependent – ndependent – XX axis. axis. This will This will insure that all of your labels are correct!insure that all of your labels are correct!
PracticePractice(If we are taking the time out of class to work on practice
problems together it is in your best interest to follow along because you might see something similar on an upcoming assessment!)
James wants to perform an experimentJames wants to perform an experimenttesting how long it takes his dog Spot to eattesting how long it takes his dog Spot to eat3 different brands of dog food.3 different brands of dog food.
What is the independent variable?What is the independent variable?What is the dependent variable?What is the dependent variable?
Practice Cont.Practice Cont.
James records that Spot finishes James records that Spot finishes Brand C in the least amount of time, Brand C in the least amount of time, James then concludes that Spot must James then concludes that Spot must like Brand C dog food the best.like Brand C dog food the best.
What is the observation?What is the observation? What is the inference? What is the inference?