INVESTIGATION AND EXPERIMENTATION INVESTIGATION AND EXPERIMENTATION

(I & e) :(I & e) : What is “Science”? What is “Science”? Observations, Inferences, and Observations, Inferences, and

Controlled ExperimentsControlled Experiments

1. 1. Science Science is an attempt to explain is an attempt to explain natural phenomenon. natural phenomenon.

2. All scientific knowledge is based on 2. All scientific knowledge is based on accurate observationsaccurate observations of the natural of the natural worldworld..

3.3. -An -An ObservationObservation an act of carefully watching an act of carefully watching something and collecting facts. something and collecting facts. -Observations are: -Observations are:

Gathered by using our senses (Gathered by using our senses (qualitativequalitative)) Can also be gathered by taking measurements Can also be gathered by taking measurements

((quantitativequantitative))

-Characteristics of good Scientific Observations: -Characteristics of good Scientific Observations:

AccurateAccurate – Quantify or measure whenever possible– Quantify or measure whenever possible Detailed and CompleteDetailed and Complete – Consider all parts of the – Consider all parts of the

observation observation RepeatableRepeatable – All observers see the same thing or – All observers see the same thing or

each time the event is observed the description is each time the event is observed the description is the samethe same

4. There are two types of observations: 4. There are two types of observations: a) a) QualitativeQualitative Observations Observations—An observation —An observation

that describes the that describes the physicalphysical characteristics or characteristics or qualities of something. qualities of something.

(Ex. The water is hot; The M&M is small; The egg (Ex. The water is hot; The M&M is small; The egg smells bad; The leaf is orange, etc)smells bad; The leaf is orange, etc)

b)b) QuantitativeQuantitative Observations Observations—An observation —An observation

that is based upon numerical information or a that is based upon numerical information or a measurementmeasurement of some type. of some type.

(Ex. The water is 45ºC; The M&M is 1.7 cm in (Ex. The water is 45ºC; The M&M is 1.7 cm in length; The car is traveling at 65 Km/hr)length; The car is traveling at 65 Km/hr)

5. Good scientific observations are used in 5. Good scientific observations are used in order to makeorder to make predictionspredictions,, or or inferencesinferences, , about the natural world. about the natural world.

6. To 6. To inferinfer means… means… to make a prediction based on to make a prediction based on observation. observation.

7. An 7. An inference inference is ais a conclusionconclusion that is formed by that is formed by using logic and what is previously understood using logic and what is previously understood about the natural world. about the natural world.

Ex Ex 8. Which statement is an 8. Which statement is an inferenceinference??a. It has 3 candles. a. It has 3 candles. b. It is a cake for some one turning 3 years old.b. It is a cake for some one turning 3 years old.c. It is a round cake with squiggly black lines.c. It is a round cake with squiggly black lines.

9. Good scientific inferences9. Good scientific inferences::a) Consider all available a) Consider all available observationsobservations..

b) Fits the understanding of b) Fits the understanding of the natural worldthe natural world c) are the c) are the most logicalmost logical and rational conclusion and rational conclusion

10. All inferences must be 10. All inferences must be based on based on previous observationsprevious observations of the natural of the natural world.world.

11. Inferences are the basis for all Scientific 11. Inferences are the basis for all Scientific Theories and HypothesesTheories and Hypotheses. .

12. What’s the difference? 12. What’s the difference? Theory vs. Law vs. Hypothesis Theory vs. Law vs. Hypothesis **A **A scientificscientific theorytheory is a well-tested is a well-tested

explanation that unifies a broad range of explanation that unifies a broad range of observations. observations.

((Ex: Theory of Plate Tectonics, Atomic Theory, Cell Ex: Theory of Plate Tectonics, Atomic Theory, Cell Theory, etc.)Theory, etc.)

--A scientific theory may be A scientific theory may be revisedrevised as new as new evidence is presented. evidence is presented.

-A theory is like the automobile.-A theory is like the automobile.--WHY?? Components of it can be changed or improved upon, without WHY?? Components of it can be changed or improved upon, without

changing the overall truth of the theory as a whole. changing the overall truth of the theory as a whole.

Scientific LawScientific Law**A **A scientificscientific lawlaw is a consistent is a consistent principle that is principle that is

repeatedly observedrepeatedly observed in nature and is usually in nature and is usually mathematical. mathematical. -It is always true.-It is always true.

(Ex: Gravity, Speed of light, the laws of thermodynamics, (Ex: Gravity, Speed of light, the laws of thermodynamics, Boyle's law of gases, the law of conservation of mass and energy. ) Boyle's law of gases, the law of conservation of mass and energy. )

A scientific law is like a slingshot. A scientific law is like a slingshot. WHY?? A slingshot has but one moving part--the rubber band. If WHY?? A slingshot has but one moving part--the rubber band. If you put a rock in it and draw it back, the rock will fly out at a you put a rock in it and draw it back, the rock will fly out at a predictable speed, depending upon the distance the band is drawn predictable speed, depending upon the distance the band is drawn back.back.

Scientific Method and Controlled ExperimentsScientific Method and Controlled Experiments

**A **A hypothesishypothesis is a testable possible is a testable possible explanation of an observation.explanation of an observation.-In science, a hypothesis is useful only -In science, a hypothesis is useful only if it can be if it can be testedtested..-Scientific hypotheses are most often -Scientific hypotheses are most often tested by the process of tested by the process of experimentingexperimenting..An An attempted explanationattempted explanation needs to be needs to be tested to be accepted. tested to be accepted.

Scientific MethodScientific MethodI. Make ObservationsI. Make ObservationsII. State the ProblemII. State the ProblemIII. Form a HypothesisIII. Form a HypothesisIV. Set up a IV. Set up a ControlledControlled Experiment ExperimentV. Record and Organize DataV. Record and Organize DataVI. Formulate a ConclusionVI. Formulate a Conclusion

Scientific MethodScientific MethodI. I. Make ObservationsMake Observations – Qualitative – Qualitative

and/or quantitative. Allows to and/or quantitative. Allows to formulate a question.formulate a question.

II. II. State the ProblemState the Problem— Form of a — Form of a questionquestion that indicates the that indicates the purpose of the investigation.purpose of the investigation.

III. III. Form a HypothesisForm a Hypothesis— A possible — A possible answeranswer to our question to our question

Or a possible explanation about an Or a possible explanation about an observation. observation.

(Hypotheses are not proven but (Hypotheses are not proven but supported by evidence)supported by evidence)

*IV. *IV. Set up a Set up a ControlledControlled Experiment Experiment—— An experiment is basically a An experiment is basically a comparisoncomparison of two situations. of two situations.

One of the situations is left One of the situations is left constantconstant, , while one factor of the other situation is while one factor of the other situation is changedchanged in order to test the affect of that in order to test the affect of that specific change. specific change.

ControlControl – a set of conditions used for – a set of conditions used for comparison purposes; can either be original comparison purposes; can either be original conditions, real-life conditions, or specific conditions, real-life conditions, or specific conditions set by the experimenterconditions set by the experimenter

There are There are three typesthree types of factors that may affect an of factors that may affect an experiment. These factors are called experiment. These factors are called variablesvariables. .

1. The factor that is purposely changed by the 1. The factor that is purposely changed by the

experimenter is called the experimenter is called the independentindependent variable variable (also called the (also called the manipulated variable)manipulated variable)..

2. The factor that changes in response to the independent 2. The factor that changes in response to the independent variable is called the variable is called the dependentdependent variable variable

(or the (or the responding variableresponding variable). ).

3. The rest of the factors that the scientists keep the same 3. The rest of the factors that the scientists keep the same in the experiment are called the in the experiment are called the controlled controlled

variablesvariables. .

It is important to test the affect of It is important to test the affect of changing only changing only oneone variable variable in order to get accurate results. in order to get accurate results.

**If only one variable is changed and all the other **If only one variable is changed and all the other factors are kept the same then we say that it is a factors are kept the same then we say that it is a controlled experiment. controlled experiment.

***Uncontrolled conditions can lead to inaccurate ***Uncontrolled conditions can lead to inaccurate results. results.

V. V. Record and Organize DataRecord and Organize Data—— - Data tables, graphs, charts, observations, etc.- Data tables, graphs, charts, observations, etc.

VI. VI. Conclusion—Conclusion—- Indicate whether or not your hypothesis was - Indicate whether or not your hypothesis was correctcorrect- Describe how the data provides evidence for - Describe how the data provides evidence for your conclusionyour conclusion Perform Perform CalculationsCalculations

- Identify possible sources of - Identify possible sources of errorerror in your in your experimentexperiment

If experiments do not prove our If experiments do not prove our hypothesishypothesis Do more Do more experimentsexperiments or . . . or . . . Formulate a new Formulate a new hypothesishypothesis and start and start

over!over!