scientific method. goal what is the scientific method? what is the scientific method? does the...
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Scientific MethodScientific Method
GoalGoal What is the scientific What is the scientific
method?method? Does the scientific method Does the scientific method
work?work? What is not a scientific What is not a scientific
argument.argument. Does biology follow the Does biology follow the
scientific method?scientific method?
Steps in the Scientific Steps in the Scientific MethodMethod
Scientific Method Car Repair
Observation Engine won’t turn over.
Predict battery is dead.
Test (_______________) Replace battery.
Observe result Engine now turns over.
Revise hypothesis? Not needed.
New test? Not needed.
Scientific Theory Cars won’t work without a fully charged battery.
Everyday ScienceScientific Method Making Spaghetti Sauce
Observation Spaghetti sauce is made of tomatoes.
Try to make tomato sauce with whole tomatoes.
Test Heat pot of tomatoes.
Observe result Taste the sauce – yuck.
Revise hypothesis? Use tomato sauce and garlic!
New test? Add garlic, taste - not so bland.
Scientific Theory The Final Recipe.
ObservationsObservations Gathered Gathered through your through your
__________________ A scientist A scientist
notices notices (wonders (wonders
about) about) something in something in
their their ____________________________
An An exampleexample of a of a scientific scientific
observationobservation might be might be
noticing that noticing that many many
salamanders salamanders near a pond near a pond
have curved, not have curved, not straight, tailsstraight, tails
HypothesisHypothesis A suggested A suggested
solution to (reason solution to (reason for) the problem or for) the problem or observationobservation An ____________An ____________
Must be Must be ________________ Sometimes written Sometimes written
as as If…Then…If…Then… statementsstatements
______________________an an outcomeoutcome
An An example of a example of a hypothesishypothesis might might be that the be that the salamanders salamanders have curved tails have curved tails due to a due to a pollutant in the pollutant in the moist soil where moist soil where they livethey live
An An Experiment Experiment is a _________ is a _________
set up to set up to testtest the the
VariableVariable – – factor in the factor in the experiment experiment that is being that is being
ExperimentExperiment A good A good (valid) (valid)
science science experiment experiment tests a tests a single single variablevariable that that can be can be measured measured against a against a control.control.
ExperimentExperiment Controlled Controlled
experiments experiments are are situations where situations where all factors are the all factors are the same between same between two test subjects, two test subjects, except for the except for the single __________single __________
The The independent independent variable variable is is
the the ________________________
____________ in ____________ in the the
Scientific Experiments Scientific Experiments Follow RulesFollow Rules
An experimenter ______________________
and observes or measures what happens.
Variables Remember, the factor that is
changed is known as the _______________________.
The factor that is measured or observed is called the _______________________. (What “happens” DEPENDS on what the
What is the Purpose of What is the Purpose of a Control?a Control?
Controls are NOT being tested
Controls are used for COMPARISON
Example of Controls & Example of Controls & VariablesVariables
For example, suppose you want to figure out the fastest route to walk home from school.
You will try several different routes and time how long it takes you to get home by each one.
Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.
What are the Variables What are the Variables in Your Experiment?in Your Experiment?
Varying (changing) the route Varying (changing) the route is the is the independent variableindependent variable
The time it takes is the The time it takes is the dependent variabledependent variable
Keeping the same walker Keeping the same walker throughout makes the throughout makes the walker a walker a control variable.control variable.
One more thing… it is best to make several trials with each independent variable.
Valid ExperimentsValid Experiments
Two groups are required --- the control & experimental groups
There should be only one variable
DataData Results of
May be quantitative (numbers) or qualitative
DataData Must be
organized Can be
organized into charts, tables, or graphs
The answer to the hypothesis based on the data obtained from the experiment
In order to verify the results,
experiments must be retested
So?????? A successful
hypothesis eventually becomes a Scientific Theory.
TheoriesTheories A theory is a highly successful A theory is a highly successful
hypothesis.hypothesis. All hypotheses make predictions.All hypotheses make predictions. All theories make predictions.All theories make predictions. All theories can be tested.All theories can be tested. Result: Any scientific theory is Result: Any scientific theory is
subject to change as our ability to subject to change as our ability to make tests, or make observations of make tests, or make observations of a test’s results, improves with time.a test’s results, improves with time.
Non-scientific TheoriesNon-scientific Theories Make no predictionsMake no predictions Un-testableUn-testable Can’t be provenCan’t be proven
Non-scientific TheoriesNon-scientific Theories Car won’t work? Car won’t work? Aliens drained the Aliens drained the
battery.battery. Spaghetti is bland? Spaghetti is bland? You were meant to You were meant to
eat bland food.eat bland food. Car won’t work? Car won’t work? Gods must be angry. Gods must be angry. Spaghetti is bland? Spaghetti is bland? At the instant of At the instant of
tasting, the tongue is transported to tasting, the tongue is transported to alternate dimension where all flavors are alternate dimension where all flavors are rendered nullified. Happens rendered nullified. Happens instantaneously.instantaneously.