The Scientific MethodThe Scientific Method

What is the Scientific What is the Scientific Method?Method? A logical problem solving process A logical problem solving process

to investigate a scientific to investigate a scientific problem.problem.

No one completely correct set of No one completely correct set of stepssteps– Depends on problem/researchDepends on problem/research

Steps in the Scientific Steps in the Scientific MethodMethod State the ProblemState the Problem ResearchResearch Form a HypothesisForm a Hypothesis Design an ExperimentDesign an Experiment Test the HypothesisTest the Hypothesis Organize the DataOrganize the Data Draw ConclusionsDraw Conclusions

State the ProblemState the Problem

Observe a discrepancyObserve a discrepancy– Doesn’t belongDoesn’t belong– UnexpectedUnexpected

Can’t solve a problem if it isn’t Can’t solve a problem if it isn’t understoodunderstood

Example: My snow peas aren’t Example: My snow peas aren’t producing many pods.producing many pods.

State the ProblemState the Problem

State the problem as a questionState the problem as a question– Can’t be answered by Yes or No.Can’t be answered by Yes or No.– Use: How, When, What, Where, and WhyUse: How, When, What, Where, and Why

Specific but not cumbersomeSpecific but not cumbersome Must be testableMust be testable Two variablesTwo variables

– IndependentIndependent– DependentDependent

Example: Will fertilizer increase snow pea pod Example: Will fertilizer increase snow pea pod production?production?

Example: What effect does fertilizer have on snow peas?Example: What effect does fertilizer have on snow peas?

Writing a Statement of Writing a Statement of the Problemthe Problem

What is the effect of chemicals?What is the effect of chemicals? What is the effect of chemicals on health?What is the effect of chemicals on health? What is the effect of vitamins on health?What is the effect of vitamins on health? What is the effect of Vitamin C on health?What is the effect of Vitamin C on health? What is the effect of Vitamin C on human What is the effect of Vitamin C on human

health?health? What is the effect of Vitamin C on the What is the effect of Vitamin C on the

occurrence of the common cold in humans?occurrence of the common cold in humans? What is the effect of What is the effect of Vitamin CVitamin C on the on the

occurrence of the occurrence of the common coldcommon cold in humans? in humans?

ResearchResearch

Find prior information about your Find prior information about your problem (background information)problem (background information)

Make initial observationsMake initial observations– Use your five sensesUse your five senses

Apply previous knowledgeApply previous knowledge– Make inferencesMake inferences

Gather factual informationGather factual information– Use books, journals, computer, etcUse books, journals, computer, etc

Form a HypothesisForm a Hypothesis

Predict what will happenPredict what will happen– Best guess or possible explanationBest guess or possible explanation– Determines a possible solutionDetermines a possible solution

Write as “If…then” or ‘If…then…Write as “If…then” or ‘If…then…than’ statement than’ statement (If = cause; Then = (If = cause; Then = effect)effect)

Must be testableMust be testable Includes two variablesIncludes two variables

– Independent Independent – DependentDependent

Independent VariablesIndependent Variables

The variable that is different or being The variable that is different or being tested.tested.

Also called the Also called the Manipulated VariableManipulated Variable ‘‘Cause’ part of Cause and EffectCause’ part of Cause and Effect Graphed on the X axisGraphed on the X axis

Example: Example: IF IF fertilizerfertilizer is used is used, THEN the , THEN the plants will produce more pea pods plants will produce more pea pods THAN the plants without the fertilizer.THAN the plants without the fertilizer.

Dependent VariablesDependent Variables

The variable that responds to changes The variable that responds to changes in the Independent Variablein the Independent Variable

Also called the Also called the Responding VariableResponding Variable ‘‘Effect’ part of Cause and EffectEffect’ part of Cause and Effect Graphed on the Y axisGraphed on the Y axis

Example: IF fertilizer is used, THEN Example: IF fertilizer is used, THEN the the plants will plants will produce more pea podsproduce more pea pods THAN the plants without the fertilizer.THAN the plants without the fertilizer.

0

5

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group1

group2

group3

group4

FertilizerWater Only

Treatment

# p

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Fig. 1. Pea Plant pod production on pea plants with and without fertilizer.

Independent Variable

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Form a Hypothesis - Form a Hypothesis - ExamplesExamplesProblem 1: What effect does fertilizer have on Problem 1: What effect does fertilizer have on

snow peas?snow peas?Hypothesis 1: IF fertilizer is used, THEN the Hypothesis 1: IF fertilizer is used, THEN the

plants will produce more pea pods THAN the plants will produce more pea pods THAN the plants without the fertilizer.plants without the fertilizer.

Problem 2: What is the effect of Vitamin C on Problem 2: What is the effect of Vitamin C on the occurrence of the common cold in the occurrence of the common cold in humans?humans?

Hypothesis 2: IF 500mg of Vitamin C is given Hypothesis 2: IF 500mg of Vitamin C is given daily, THEN it will prevent the common cold in daily, THEN it will prevent the common cold in humans.humans.

Design an ExperimentDesign an Experiment

Establish at least two test groupsEstablish at least two test groups– Experimental-the independent Experimental-the independent

variable is applied to this groupvariable is applied to this group– Control-comparison or normal group; Control-comparison or normal group;

no independent variable appliedno independent variable applied Provide a list of materialsProvide a list of materials Develop a procedureDevelop a procedure

– Explains what is to be done and Explains what is to be done and whenwhen

Test GroupsTest Groups

Pea PlantsPea Plants Control group: Control group: Test or Experimental Group:Test or Experimental Group:

Vitamin CVitamin C Control group:Control group: Test or Experimental Group:Test or Experimental Group:

WaterWaterFertilizerFertilizer

Placebo (no vit. C)Placebo (no vit. C)

500 mg Vitamin C 500 mg Vitamin C dailydaily

Controlled Variables Controlled Variables (Constants)(Constants)

Factors that remain the same throughout Factors that remain the same throughout the experimentthe experiment

Are the same for both the control and Are the same for both the control and experimental groups.experimental groups.

Don’t changeDon’t change Includes everything Includes everything exceptexcept the the

independent variableindependent variable

Pea Plants: water, light, temperature, etcPea Plants: water, light, temperature, etcVitamin C: age, sex, weight, diet, etcVitamin C: age, sex, weight, diet, etc

Test the HypothesisTest the Hypothesis

Make sure all variables are controlledMake sure all variables are controlled Follow the procedureFollow the procedure Record your observationsRecord your observations Record any mistakes, accidents, Record any mistakes, accidents,

weather, etc. that might affect the weather, etc. that might affect the resultsresults

The experiment provides evidence for The experiment provides evidence for or against the hypothesisor against the hypothesis

Collect DataCollect Data

Use logs, journals, tables and Use logs, journals, tables and graphsgraphs

Record all observationsRecord all observations– Include things you don’t think are Include things you don’t think are

importantimportant– Qualitative Data Qualitative Data – Quantitative Data Quantitative Data

Include time, units, duration, # Include time, units, duration, # trials or sets, etc.trials or sets, etc.

Be specific!Be specific!

Organize the DataOrganize the Data

Daily LogDaily Log GraphsGraphs

– Continuous dataContinuous data– Discontinuous data Discontinuous data

TablesTables– Repetitive dataRepetitive data

DayDay DatDatee

TimeTime TempTemp Comments and ObservationsComments and Observations

11 5/145/14 9 am9 am 9999 Planted seed and placed in direct sunlight Planted seed and placed in direct sunlight for 6 hoursfor 6 hours

2-2-1010

2323 9 am9 am Avg. Avg. 9898

Sprouts are showing in both groupsSprouts are showing in both groups

1111 2424 9 am9 am 9696 No discernable difference between groupsNo discernable difference between groups

1212 2525 9 am9 am 9595 SameSame

1313 2626 9 am9 am 9191 Same growth rate; approx. 6 in tall.Same growth rate; approx. 6 in tall.

1414 2727 9 am9 am 9999 Plants are growing full sized leavesPlants are growing full sized leaves

Daily Log

The Effect of Fertilizer on Pea Production – Daily Log

Graphs or FiguresGraphs or Figures

Visual representationVisual representation Shows relationshipsShows relationships Title at the BOTTOM!Title at the BOTTOM! Includes:Includes:

– Pictures (Figures)Pictures (Figures)– Bar graphs Bar graphs

Discontinuous dataDiscontinuous data

– Line graphs Line graphs Continuous dataContinuous data

– Pie chartsPie charts

Discontinuous DataDiscontinuous Data

Sharp, dramatic differencesSharp, dramatic differences Either – Or, no blendingEither – Or, no blending

Examples:Examples:– color color – GradeGrade– sexsex

Graphs or Figures Graphs or Figures Discontinuous DataDiscontinuous Data

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group1

group2

group3

group4

FertilizerWater Only

Treatment

# p

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pods

Fig. 1. Pea Plant pod production on pea plants with and without fertilizer.

Independent Variable

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Title

Continuous DataContinuous Data

Regular, gradual changes Regular, gradual changes Shows linear relationshipsShows linear relationshipsExamples:Examples:

– DistanceDistance– TemperatureTemperature– TimeTime– WeightWeight– HeightHeight– AgeAge

Graphs or Figures- Graphs or Figures- Continuous DataContinuous Data

Time (Min.)

Revolu

tion

s

Fig. 1. Revolutions of an exercise wheel powered by a hamster over time.

Independent Variable

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Title

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0 5 10 15 20

TablesTables

Repetitive dataRepetitive data Like elements read downLike elements read down

– Compact and easy to readCompact and easy to read Title goes at the TOP!Title goes at the TOP!

HeadingHeading HeadingHeading HeadingHeading

Related dataRelated data Related dataRelated data Related dataRelated data

Table 1: How to correctly set up a table.Table 1: How to correctly set up a table.

TablesTables

FertilizerFertilizer WaterWater

Group 1Group 1 1818 1010

Group 2Group 2 2121 88

Group3Group3 1515 1111

Group4Group4 1212 1010

TotalTotal 6666 3939

AverageAverage 16.516.5 9.759.75

Table 1: The number of pea pods produced for each treatment per group of pea plants.

Title

Draw ConclusionsDraw Conclusions

Analyze your data and summarize Analyze your data and summarize your findings.your findings.

Is a judgment based on the Is a judgment based on the resultsresults

Can agree, disagree, or reveal Can agree, disagree, or reveal nothing about the hypothesisnothing about the hypothesis

State potential flawsState potential flaws

Publish and/or Repeat Publish and/or Repeat

Publish in a peer-reviewed journalPublish in a peer-reviewed journal Allows others to critique and testAllows others to critique and test

Important research:Important research: Design different experiments to Design different experiments to

test the hypothesis or generate test the hypothesis or generate additional hypotheses.additional hypotheses.