Scientific MethodScientific Method

Steps in the Scientific Steps in the Scientific MethodMethod

Observation/Observation/State a problemState a problem

ResearchResearch HypothesisHypothesis ExperimentExperiment Data CollectionData Collection ConclusionConclusion RetestRetest

Observations(State Observations(State the problem)the problem)

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

Research Find out as much

information as you can on the problem

Become educated on the problem

Find other scientists who have done similar research

HypothesisHypothesis

PredictsPredicts an an outcomeoutcomeA suggested A suggested solution to the solution to the problem.problem.Must be Must be testabletestableSometimes Sometimes written as written as If…If…Then…Then… statementsstatements

HypothesisHypothesis

An An example of a example of a hypothesis:hypothesis:

If I add salt to If I add salt to water then the water then the water will boil water will boil quicker.quicker.

ExperimentExperiment

A A procedure procedure to to testtest the the hypothesishypothesis

..

ExperimentAll experiments MUST contain the

following parts: a. Variables-Independent and

Dependentb. Control Group c. Experimental Groupd. Datae. Controlled Variables (Constants)

Independent VariableIndependent Variable

Independent Independent VariableVariable – factor – factor

that is being that is being testedtested

Factor that YOU Factor that YOU change in an change in an experimentexperiment

Independent Independent VariableVariable

A good or A good or “valid” “valid”

experiment experiment will only will only

have have ONE ONE independent independent

variable!variable!

Dependent Variable Dependent

variable. The factor that is measured or observed

Results from the independent variable

Data that can be recorded

Scientific Experiments Scientific Experiments Follow RulesFollow Rules

An experimenter changes one factor (IV) and observes or measures DV) what happens.

The Controlled The Controlled Variables (Constants)Variables (Constants) 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.

Control Group vs. Control Group vs. Experimental GroupExperimental Group

Control Group Does not contain

the variable and is NOT being tested

The Control group is used for COMPARISON only.

Experimental Group The experiment

that contains the IV variable

May have more than one exp. group

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 IV variable

DataData Results of

the experiment

May be quantitative (numbers) or qualitative

Examples of Data

Quantitative Data using

numbers

Qualitative Describing our

observations during the experiment.

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.

ReviewReview

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