chp. 1.1 1.2 notes

Chapter 1.1-1.2 NotesChapter 1.1-1.2 Notes

ScienceScience: is an organized : is an organized way of using evidence to way of using evidence to learn about the natural learn about the natural worldworld

Scientific thinking usually Scientific thinking usually begins with:begins with:ObservationsObservations: the process of : the process of gathering information about gathering information about events or processes in a events or processes in a careful, orderly way. careful, orderly way. Observations generally involve Observations generally involve using the senses.using the senses.

Information gathered from Information gathered from observations is called observations is called datadata..

Quantitative dataQuantitative data: : expressed as numbers, expressed as numbers, obtained by counting or obtained by counting or measuringmeasuring

Qualitative dataQualitative data: descriptive : descriptive and involve and involve characteristics characteristics that can’t usually be that can’t usually be countedcounted

Scientists may use data to Scientists may use data to make make inferencesinferences..• IInference: nference: an interpretation an interpretation

or explanation of an or explanation of an

observation.observation.

After initial observations, After initial observations, scientists propose one or more scientists propose one or more hypothesishypothesis..

HypothesisHypothesis:: a proposed a proposed scientific explanation for a set scientific explanation for a set of observations. Scientists of observations. Scientists generate hypothesis based on generate hypothesis based on prior knowledge, logical prior knowledge, logical inference, and informed inference, and informed creative imagination.creative imagination.

Scientific hypotheses must be Scientific hypotheses must be proposed in a way that enables proposed in a way that enables them to be tested.them to be tested.

Science is a way of knowingScience is a way of knowingscience is an ongoing processscience is an ongoing processscientific understanding is scientific understanding is always changing.always changing.

Good scientists are skeptics.Good scientists are skeptics.

Scientists assume that in the Scientists assume that in the universe, basic natural laws universe, basic natural laws govern all events and objects.govern all events and objects.

Scientific MethodScientific Method

• Identify a problemIdentify a problem

• Gather Information (research)Gather Information (research)

• Make hypothesesMake hypotheses

• Test the hypothesesTest the hypotheses

• Analyze the resultsAnalyze the results

• Draw conclusionsDraw conclusions

VariablesVariables: : The factors in an The factors in an experiment that can change.experiment that can change.Examples: equipment used, Examples: equipment used, type of material, amount of type of material, amount of material, temperature, light, material, temperature, light, time, etc.time, etc.

Whenever possible, a Whenever possible, a hypothesis should be hypothesis should be tested by an experiment in tested by an experiment in which only which only ONE variableONE variable is is changed at a time! changed at a time!

This type of experiment is This type of experiment is called a called a controlled experiment controlled experiment

The variable that is The variable that is changed is called the changed is called the manipulated or independentmanipulated or independent variable.variable.

The variable that is The variable that is observed and that changes observed and that changes in response to the in response to the manipulated variable is manipulated variable is called the called the responding or responding or dependent variable dependent variable

ConstantsConstants

• Variables in experiment that need to Variables in experiment that need to stay the same!!stay the same!!

ControlControl

• a standard to which your a standard to which your experiments can be compared.experiments can be compared.

ExampleExample• Problem – which type of dish soap Problem – which type of dish soap

works the best???works the best???

• Hypothesis – Dawn works the best at Hypothesis – Dawn works the best at washing grease off of a pan.washing grease off of a pan.

Independent VariableIndependent Variable• type of soap usedtype of soap used

Dependent VariableDependent Variable- how much grease is left on pan (what you - how much grease is left on pan (what you

measure!!!)measure!!!)

ConstantsConstants- types of pans, amount of soap, temperature of types of pans, amount of soap, temperature of

water, type of washer, etc.water, type of washer, etc.

ControlControl- wash a pan without any soap!!!wash a pan without any soap!!!

Recording and Analyzing Recording and Analyzing ResultsResultsOften done with technologyOften done with technology

Experiments Must Be Experiments Must Be RepeatedRepeated

• you cannot do an experiment once you cannot do an experiment once and get valid resultsand get valid results

Drawing A ConclusionDrawing A Conclusion

• use the data from an experiment to use the data from an experiment to evaluate the hypothesis and draw a evaluate the hypothesis and draw a conclusionconclusion

Science assumes that Science assumes that experimental results can be experimental results can be reproduced because nature reproduced because nature behaves in a consistent behaves in a consistent mannermanner

Scientists often publish reports Scientists often publish reports in scientific journals, where in scientific journals, where other scientists review the other scientists review the experiments to make sure experiments to make sure there were no flaws. there were no flaws.

Scientists also often repeat Scientists also often repeat experiments done by others to experiments done by others to check for flaws.check for flaws.

When Experiments are Not When Experiments are Not PossiblePossible • ethical considerationsethical considerations

– example: determining the effect example: determining the effect

on people of a chemical suspected on people of a chemical suspected

of causing cancerof causing cancer

How a Theory DevelopsHow a Theory Develops• As evidence from numerous As evidence from numerous

investigations builds up, a investigations builds up, a particular hypothesis may particular hypothesis may become so well supported that become so well supported that scientists consider it a theoryscientists consider it a theory

Scientific Theory: Scientific Theory: a well a well tested explanation that unifies tested explanation that unifies a broad range of observations.a broad range of observations.

Scientific LawScientific Law

• theory that has never (and scientists theory that has never (and scientists think will never) be disproventhink will never) be disproven

• A theory or a law enables scientists A theory or a law enables scientists to make accurate predictions about to make accurate predictions about new situations.new situations.

– No theory or law is considered absolute No theory or law is considered absolute truthtruth

– Theories and laws may be revised or Theories and laws may be revised or replaced.replaced.