Scientific MethodScientific Method
Steps in the Scientific Steps in the Scientific MethodMethod
ObservationObservation HypothesisHypothesis ExperimentExperiment Data CollectionData Collection ConclusionConclusion RetestRetest
ObservationsObservations
Gathered Gathered through your through your
sensessenses A scientist A scientist
notices notices something in something in their their natural natural
worldworld
ObservationsObservations
An An exampleexample of of an observationan observation
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 the solution to the problem.problem.
Must be Must be testabletestable Sometimes Sometimes
written as written as If…If…Then…Then… statementsstatements
PredictsPredicts an an outcomeoutcome
HypothesisHypothesis
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 live. they live.
ExperimentExperiment
A A procedure procedure to to testtest the the hypothesishypothesis
..
ExperimentExperiment
VariableVariable – – factor in the factor in the experiment experiment that is being that is being
testedtested
ExperimentExperiment
A good or A good or “valid” “valid”
experiment experiment will only will only
have have ONE ONE variable!variable!
Controls and VariablesControls and Variables
Scientific Experiments Scientific Experiments Follow RulesFollow Rules
An experimenter changes one factor and observes or measures what happens.
The Control VariableThe Control Variable The experimenter makes a The experimenter makes a
special effort to keep special effort to keep other factors constantother factors constant so so that they will not effect that they will not effect the outcome.the outcome.
Those factors are called Those factors are called control variables.control variables.
What is the Purpose of What is the Purpose of a Control?a Control?
Controls are NOT being tested
Controls are used for COMPARISON
Other Variables The factor that is changed
is known as the independent variable.
The factor that is measured or observed is called the dependent variable.
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 the route is the Varying the route 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
Remember: To be a Remember: To be a Valid Experiment:Valid Experiment:
Two groups are required --- the control & experimental groups
There should be only one variable
DataData Results of
the experiment
May be quantitative (numbers) or qualitative
DataData Must be
organized Can be
organized into charts, tables, or graphs
ConclusionConclusion
The answer to the hypothesis based on the data obtained from the experiment
RetestRetest
In order to verify the results,
experiments must be retested.
Solving a ProblemSolving a Problem1)Identify a Problem2) State Observations
about the problem3) Form a Hypothesis
about the problem (if…then…)
4) Design an Experiment to test the hypothesis
5) Collect Data6) Form a Conclusion7) Retest
RERUN R Restate the purpose of the
experiment. For some labs, you may be given the purpose and for others you may have to reword the question. This can normally be completed in one sentence. (The purpose of this lab was to …).
RERUN E Summarize the experiment. What
did you do in this lab? Give enough details that one with some science background could follow the steps with out much assistance. For some labs, this can be completed in two or three sentences. For other labs, it may take six to eight sentences. (In this lab we …).
RERUN R Analyze the results. Three main items should be
included in this section. First, restate the hypothesis. Next, give actual data. Remember, this can be done with quantitative and/or qualitative observations. Finally, state whether the hypothesis was supported or rejected. You are only conducting this experiment once. You will NOT be able to prove any concept to be right, wrong, correct or incorrect. This section of the RERUN will take a complete paragraph to complete. If a lab has more than one hypothesis, you may need more than one paragraph. (My hypothesis was …). (The data shows …). And, (The hypothesis was …).
RERUN U Describe any uncertainties or
problems that you had. What could have gone wrong? You should be able to complete this section in two or three sentences. (One problem that I had …). Or, (One thing that may have gone wrong was …).
RERUN N What can you do now? How
could you apply this lab in your life? Or, how could we change this lab in the future? (One way to use in this information would be …). Or, (One new thing I learned was …).