How is Science Made?How is Science Made?

ObservationObservation

1.1. ObservationObservation:: See that there is See that there is a problem.a problem.

-Most students recognized that -Most students recognized that there was a big stain on my shirt there was a big stain on my shirt

-Make sure there is only one -Make sure there is only one problem being studied!!!problem being studied!!!

Research the ProblemResearch the Problem

Look up everything you can on your topicLook up everything you can on your topic Visit your library or go on the internetVisit your library or go on the internet Conduct personal interviewsConduct personal interviews Search for articles (magazines, Search for articles (magazines,

journals, books, newspapers) that have journals, books, newspapers) that have been written about the topic you are been written about the topic you are interested ininterested in

Hypothesis

2. Hypothesis: an educated guess-Possible answers to questions generated by

your observations

-Typically written as an “if and then” statement

-“If’ =hypothesis-“Then” = results received after the controlled

experiment.

Example of “if” “then” hypothesisExample of “if” “then” hypothesis

""IfIf a plant receives fertilizer, a plant receives fertilizer, thenthen it it will grow to be bigger than a plant will grow to be bigger than a plant that does not receive fertilizer.”that does not receive fertilizer.”

**It involves a prediction, which **It involves a prediction, which explains the problem. explains the problem.

Ex. of a prediction:Ex. of a prediction: The spot on Mrs. The spot on Mrs. Gates shirt is oil Gates shirt is oil

Then use that prediction to make a Then use that prediction to make a hypothesis. hypothesis.

Ex: If the spot on Mrs. Gates shirt is Ex: If the spot on Mrs. Gates shirt is oil, then the spot should look and oil, then the spot should look and smell like oil.smell like oil.

ExperimentExperiment• 3. Experiment:

Develop and conduct a controlled experiment.

• -Test one variable at a time

Ex: compare the smell on my shirt to Ex: compare the smell on my shirt to regular oil. Dump oil on an identical regular oil. Dump oil on an identical shirt and see if the spots look similar. shirt and see if the spots look similar. Also put ink, paint, and dirt on the Also put ink, paint, and dirt on the same shirt and compare those spots same shirt and compare those spots to the “mystery spot.”to the “mystery spot.”

An experiment must have a controlled variable An experiment must have a controlled variable and a manipulated variableand a manipulated variable

Control:Control: Serves as a standard for Serves as a standard for comparison. The control must remain the comparison. The control must remain the same throughout the experiment. same throughout the experiment. Ex: the shirt Ex: the shirt that I am wearing will be the control.that I am wearing will be the control.

Variable:Variable: A variable that is being changed in A variable that is being changed in the experiment. the experiment. Ex: the spots of ink, paint, dirt, Ex: the spots of ink, paint, dirt, and oil are the variables in this experiment.and oil are the variables in this experiment.

Qualitative vs. Quantitative Qualitative vs. Quantitative DataData

QuantitativeQuantitative-Data that uses numbers-Data that uses numbers-(Height- John is 6’2” Weight- 195 lbs )-(Height- John is 6’2” Weight- 195 lbs )

QualitativeQualitative-Descriptive, no numbers-Descriptive, no numbers-Involves characteristics that -Involves characteristics that can’t be measured can’t be measured -Ex. Study of how -Ex. Study of how gorillas behavegorillas behave

A. Control setupA. Control setupSetup in which all conditions Setup in which all conditions are kept the sameare kept the sameB. Experimental setupB. Experimental setupSetup in which all conditions Setup in which all conditions are kept the same except for are kept the same except for the one being testedthe one being testedC. Independent variableC. Independent variableThe condition (variable) being The condition (variable) being changed by youchanged by youD. Dependent variableD. Dependent variableThe condition (variable) being The condition (variable) being observed or measuredobserved or measured in the in the experimentexperiment

Problem: Does the level of Problem: Does the level of iron in a mouse’s diet affect iron in a mouse’s diet affect the number of its red blood the number of its red blood cells?cells?A. Control setupA. Control setupNormal mouse feed (what is Normal mouse feed (what is normally fed to the mouse normally fed to the mouse everyday)everyday)B. Experimental setupB. Experimental setupMouse fed different levels of Mouse fed different levels of iron in the feediron in the feedC. Independent variableC. Independent variableDifferent amounts of iron Different amounts of iron added/subtracted from the added/subtracted from the feedfeedD. Dependent variable D. Dependent variable Number of red bloodNumber of red blood cellscells

Components of a controlled Components of a controlled experimentexperiment

Record ResultsRecord Results

4. 4. Record results:Record results: Scientists must Scientists must keep accurate records of data and keep accurate records of data and observations. observations.

Ex: write down the differences and Ex: write down the differences and similarities of the different spots.similarities of the different spots.

Analyze ResultsAnalyze Results

5. 5. Analyze results:Analyze results: Make sense of Make sense of the data. the data. Ex: which spots smelled and looked Ex: which spots smelled and looked

more similar to the “mystery spot.” more similar to the “mystery spot.”

ConclusionConclusion

6. 6. Make a conclusion:Make a conclusion: Was your Was your hypothesis supported or proven false. hypothesis supported or proven false. You cannot “prove” a hypothesis You cannot “prove” a hypothesis after just one experiment. It is after just one experiment. It is notnot correct to say that the hypothesis was correct to say that the hypothesis was proven correct. proven correct.

It is correct to say that the data It is correct to say that the data supports my hypothesis. supports my hypothesis.

Ex: the data supported our Ex: the data supported our hypothesis that the spot on Mrs. hypothesis that the spot on Mrs. GatesGates shirt was oil. shirt was oil.

Scientific Method Flowchart

Observation

Hypothesis

Experiment

Record Results

Analyze Results

Conclusion

Redi’s Experiment on Spontaneous generation

Spontaneous generation: About 400 years ago, scientists believed that life arose from non-living matter. Ex: the spot of oil on my shirt will spontaneously turn into a bird!!!

People once thought that meat magically transforms into flies.

Francesco Redi (1668) designed a controlled experiment to try and prove this idea false.

Needham and Spallanzani’s experiments Needham was not convinced that

spontaneous generation did not exist!!!

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.PROCEDURE

Controlled Variables:jars, type of meat,location, temperature,time

Manipulated Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appear

Responding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Redi’s Experiment on Spontaneous Generation

Spallanzani’s Experiment

Gravy is boiled.Flask isopen. Gravy is teeming

with microorganisms.

Gravy is boiled.Flask issealed.

Gravy is free of microorganisms.

Observation vs. InferenceObservation vs. Inference

Observation:Observation:

--Interpretation using one or more of the Interpretation using one or more of the senses. senses.

Ex: That object is big, green, soft, and heavyEx: That object is big, green, soft, and heavy

Inference:Inference:

-Is an interpretation based on ones prior -Is an interpretation based on ones prior knowledge and/or experience. knowledge and/or experience.

Ex: The sun makes that tree grow tall . Ex: The sun makes that tree grow tall .

Observation or Inference?

Statement Observation Inference

Object A is round and orange.

Object A is a basketball.

Object C is round and black and white.

Object C is larger than Object B.

Object B is smooth.

Object B is a table-tennis ball.

Each object is used in a different sport.

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