Scientific InquiryScientific Inquiry

08.24.07 / 08.27.0708.24.07 / 08.27.07

RecapRecap

We make an observation, ask a question, We make an observation, ask a question, and then make a hypothesis.and then make a hypothesis.

A hypothesis must be __________.A hypothesis must be __________.

So, how do we do that?So, how do we do that?

Scientific InquiryScientific Inquiry

ExperimentsExperiments (aka controlled experiments) (aka controlled experiments)

the research is conducted in a the research is conducted in a controlled setting to prevent more than controlled setting to prevent more than one variable from affecting the one variable from affecting the outcome.outcome.

InvestigationsInvestigations

used when controlled experiments are used when controlled experiments are not possiblenot possible

Scientific InquiryScientific Inquiry

As the research is conducted, data are As the research is conducted, data are gathered.gathered.

The data are then analyzed to reach a The data are then analyzed to reach a conclusionconclusion

Either the data support the hypothesis or Either the data support the hypothesis or the data refute the hypothesis. But, the the data refute the hypothesis. But, the data data never provenever prove the hypothesis. the hypothesis.

Scientific InquiryScientific Inquiry

If the data support the hypothesis, we If the data support the hypothesis, we keep the hypothesis for more testing. After keep the hypothesis for more testing. After all, it wasn’t proven, just supported.all, it wasn’t proven, just supported.

If the data refute the hypothesis, we reject If the data refute the hypothesis, we reject the hypothesis or modify it to fit the data. the hypothesis or modify it to fit the data. Then we test some more.Then we test some more.

Scientific ProgressScientific ProgressScientific knowledge is gained through:Scientific knowledge is gained through:

-- -- Following systematic stepsFollowing systematic steps• Collecting facts (observing)Collecting facts (observing)• Developing a hypothesis Developing a hypothesis • Researching (experiments / investigations)Researching (experiments / investigations)• Reexamining the hypothesis to support, Reexamining the hypothesis to support,

modify, or rejectmodify, or reject

-- Theories that withstand examination -- Theories that withstand examination

-- Totally unexpected occurrences -- Totally unexpected occurrences

The outlineThe outlineSo, scientists generally:So, scientists generally:

Make observationsMake observationsAsk a questionAsk a questionForm a hypothesisForm a hypothesisTest the hypothesisTest the hypothesisAnalyze the resultsAnalyze the resultsDraw conclusionsDraw conclusionsCommunicate results (It’s not done Communicate results (It’s not done

until until it’s communicated.)it’s communicated.)

make observations

ask a question

form a hypothesis

test the hypothesis

analyze the results

draw conclusions

Do they support the hypothesis?

no

yes communicate results

Note: You can always move backward, too.

““Inventing hypotheses or theories to imagine Inventing hypotheses or theories to imagine how the world works and then figuring out how the world works and then figuring out how they can be put to the test of reality is how they can be put to the test of reality is as creative as writing poetry, composing as creative as writing poetry, composing music, or designing skyscrapers.”music, or designing skyscrapers.”

F. James Rutherford & Andrew Ahlgren. (1990). F. James Rutherford & Andrew Ahlgren. (1990). Science Science for all Americansfor all Americans. New York: Oxford University Press. . New York: Oxford University Press.

Check-upCheck-up

Why can’t scientists always progress in an Why can’t scientists always progress in an exact sequence of steps through their exact sequence of steps through their research process?research process?

Why is it sometimes necessary to go Why is it sometimes necessary to go backward in the research process?backward in the research process?

Scientific ResearchScientific Research

Scientists measure their Scientists measure their variablesvariables. .

Experiments have two types of variables:Experiments have two types of variables:

independent variableindependent variable

purposely changed to look for a purposely changed to look for a resulting change in the dependentresulting change in the dependent

dependent variabledependent variable

measured to detect change as a measured to detect change as a result of independentresult of independent

Scientific ResearchScientific Research

I wonder how I can get better grades in I wonder how I can get better grades in science?science?

I think if I take notes in science, I’ll do I think if I take notes in science, I’ll do better on tests.better on tests.

I’ll take notes during the next unit I’ll take notes during the next unit ((independent variableindependent variable).).

I’ll see if taking notes affects my grade on I’ll see if taking notes affects my grade on the unit test (the unit test (dependent variabledependent variable).).

Scientific ResearchScientific Research

Measurements need to be as Measurements need to be as accurateaccurate and and preciseprecise as possible. as possible.

Measurement tools need to be Measurement tools need to be reliablereliable and and validvalid. .

Scientific ResearchScientific Research

Experiments have two types of variables, Experiments have two types of variables, and all other factors are kept constant, as and all other factors are kept constant, as much as possible. much as possible.

The constants are the The constants are the control variablescontrol variables. .

Experiments have a Experiments have a controlcontrol. . The control The control acts as a standard for comparison.acts as a standard for comparison.

Scientific ResearchScientific Research

In my test of note-taking’s affect on In my test of note-taking’s affect on grades, I need to grades, I need to controlcontrol as many other as many other factors as possible (e.g., keep subject the factors as possible (e.g., keep subject the same from one test to another, keep same from one test to another, keep difficulty the same, do all other studying difficulty the same, do all other studying just as before, etc).just as before, etc).

Scientific ResearchScientific Research

I need to make sure my measurements I need to make sure my measurements are are accurateaccurate and and preciseprecise..

Does the test Does the test accuratelyaccurately measure how measure how much I learned?much I learned?

Does the test measure Does the test measure preciselyprecisely enough enough to detect differences? For example, a % to detect differences? For example, a % grade is more precise than a letter grade.grade is more precise than a letter grade.

Scientific ResearchScientific Research

I need to make sure my measurements are I need to make sure my measurements are reliablereliable and and validvalid..

A A reliablereliable test will give the same results test will give the same results every time it is used for the same purpose.every time it is used for the same purpose.

A broken clock is reliable.A broken clock is reliable.

A A validvalid test correctly measures what it was test correctly measures what it was designed to measure.designed to measure.

An properly working atomic clock is valid.An properly working atomic clock is valid.

Scientific ResearchScientific ResearchDoes my science test give Does my science test give reliablereliable results? results? If I take it in the morning, will the results be If I take it in the morning, will the results be the same if I take it in the afternoon?the same if I take it in the afternoon?Does my science test give Does my science test give validvalid results? results? Does the grade I receive on the test truly Does the grade I receive on the test truly report my learning of the content of the report my learning of the content of the unit? unit? A valid measure must be reliable, but a A valid measure must be reliable, but a measure can be reliable without being measure can be reliable without being valid. valid.

Check-upCheck-up

What is the difference between reliability What is the difference between reliability and validity?and validity?

What is the difference between accuracy What is the difference between accuracy and precision?and precision?

Why are reliability, validity, accuracy and Why are reliability, validity, accuracy and precision important in science?precision important in science?

Scientific ResearchScientific ResearchIdeally, we’d have a Ideally, we’d have a control groupcontrol group..

One group of students, randomly selected, One group of students, randomly selected, would take notes during class. Another would take notes during class. Another group, randomly selected, would not take group, randomly selected, would not take notes. The second group is the control notes. The second group is the control group. group.

Then, we’d compare test scores at the end Then, we’d compare test scores at the end of the unit. Did the test group (took notes) of the unit. Did the test group (took notes) do better than the control group?do better than the control group?

Scientific ResearchScientific Research

If the test group averages higher test If the test group averages higher test grades than the control group, our grades than the control group, our hypothesis has been supported, hypothesis has been supported, but not but not provenproven..

If the test group does not earn higher If the test group does not earn higher grades, than the hypothesis has not been grades, than the hypothesis has not been supported.supported.

Check-upCheck-up1) What are the major branches of science?1) What are the major branches of science?2) How do these branches work 2) How do these branches work

interdependently to help us understand the interdependently to help us understand the world?world?

3) Explain why science is considered a 3) Explain why science is considered a process.process.

4) What do these terms mean?4) What do these terms mean?hypothesis, experiment, investigation, hypothesis, experiment, investigation, theory, law, control, variabletheory, law, control, variable

Check-upCheck-upDesign an experiment to test the Design an experiment to test the hypothesis: “Pine floats better than oak.”hypothesis: “Pine floats better than oak.”What are your variables?What are your variables?What is your control?What is your control?What variables will need to be controlled?What variables will need to be controlled?What will you measure? What tools will What will you measure? What tools will you need to use? you need to use? Make sure to discuss issues of accuracy, Make sure to discuss issues of accuracy, precision, reliability and validity.precision, reliability and validity.

HomeworkHomework

Plan an experiment to test this hypothesis:Plan an experiment to test this hypothesis:

32 psi is the optimal tire pressure for a 32 psi is the optimal tire pressure for a 2007 Ford Focus 4-door’s gas mileage. 2007 Ford Focus 4-door’s gas mileage.