• Use the Scientific Use the Scientific MethodMethod

What is an observation?What is an observation?

When you observe, you become When you observe, you become aware of something using one of aware of something using one of your senses. Your five senses are your senses. Your five senses are smell, taste, sight, touch, and smell, taste, sight, touch, and sound. sound. In an observation you In an observation you simply describe something as it simply describe something as it appears. appears. An observation is a An observation is a statement describing a fact.statement describing a fact.

ObservationObservation

In the space below, record 5 In the space below, record 5 observations about your science observations about your science classroom.classroom.1.1.2.2.3.3.4.4.5.5.

Sometimes scientists must make very Sometimes scientists must make very careful observations. Often their senses are careful observations. Often their senses are not good enough. There are some things not good enough. There are some things that cannot be observed using just your that cannot be observed using just your senses. (Examples: radiation, sound waves, senses. (Examples: radiation, sound waves, planets, cells, etc.)planets, cells, etc.)

What is an inference?What is an inference?

When you When you inferinfer, you make a , you make a mental judgmentmental judgment based on observations. Inferences based on observations. Inferences cannotcannot be be directly observeddirectly observed. They require . They require thoughtthought. For . For example, if you get up in the morning, look up at example, if you get up in the morning, look up at the sky and the sky and observe dark clouds, observe the airobserve dark clouds, observe the air is cool and humidis cool and humid, and observe puddles on the , and observe puddles on the ground, you might ground, you might inferinfer that it has recently that it has recently rained.rained. Note: you did Note: you did not see rainnot see rain; you ; you decideddecided that it rained based on your that it rained based on your observations. Anobservations. An inference is a statement based on your inference is a statement based on your interpretation of the facts. interpretation of the facts.

1.1. The idea that life could arise from The idea that life could arise from nonliving matter is known as nonliving matter is known as spontaneous generation.spontaneous generation.

2. 2. Today, we know that the Today, we know that the above is above is NOTNOT true. One of the true. One of the scientists that helped to scientists that helped to disprove the idea worked with disprove the idea worked with flies and meatflies and meat. His name is . His name is Francesco Redi.Francesco Redi.

SCIENTIFIC METHODSCIENTIFIC METHOD

I. I. Observations Observations (along with (along with inferencesinferences))

II. Stating the II. Stating the ProblemProblem

III. Forming a III. Forming a HypothesisHypothesis.”if ..then.”if ..then

Statement”Statement”

IV. Setting up a IV. Setting up a Controlled ExperimentControlled Experiment..

In science, In science, testingtesting a hypothesis often a hypothesis often involves involves designingdesigning an experiment. an experiment.

In a In a controlled controlled experiment, experiment, only only oneone variable variable is tested is tested at a time.at a time.

The variable that is The variable that is deliberately changeddeliberately changed is is called the called the manipulatedmanipulated or or independent independent variable.variable.

The variable that is The variable that is observedobserved and that and that changeschanges in responsein response to the to the manipulated or manipulated or independent variable is independent variable is called the called the respondingresponding or or dependentdependent variable. variable.

V. V. RecordingRecording and and AnalyzingAnalyzing ResultsResults..

Scientists usually keep written records Scientists usually keep written records of their observations, or of their observations, or datadata..

There are two types of data:There are two types of data:

1. 1. QualitativeQualitative: descriptions, : descriptions, behaviors, actionsbehaviors, actions

2. 2. QuantitativeQuantitative: numbers, : numbers, measurementsmeasurements

VI. Drawing a VI. Drawing a ConclusionConclusion..

Scientists use the Scientists use the data data from an from an experiment to experiment to evaluateevaluate the the hypothesis and draw a hypothesis and draw a conclusionconclusion..

That is, they use the evidence to That is, they use the evidence to determine whether the determine whether the hypothesis was hypothesis was supportedsupported or or found false (“found false (“refutedrefuted” or not ” or not true).true).

Redi’s Experiment on Spontaneous Redi’s Experiment on Spontaneous GenerationGeneration

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

HYPOTHESISHYPOTHESIS: Flies produce maggots.: Flies produce maggots.

PROCEDUREPROCEDURE::

Controlled Variables:Controlled Variables:

Jars, type of meat, location, Jars, type of meat, location, temperature, timetemperature, time

ManipulatedManipulated

VariableVariable: : gauze covering that keeps gauze covering that keeps flies away from meat.flies away from meat.

Responding Variable:Responding Variable:

Whether maggotsWhether maggots

AppearAppear

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

4. Give an example when an experiment is 4. Give an example when an experiment is NOT possible.NOT possible.

Field Studies (too many variables)Field Studies (too many variables)

5. When 5. When evidenceevidence from many investigations from many investigations supportsupport a hypothesis, scientists consider it a hypothesis, scientists consider it a a theorytheory..

http://www.goldiesroom.org/Multimedia/Movie_Clips/99%20Labs/http://www.goldiesroom.org/Multimedia/Movie_Clips/99%20Labs/Variables%20and%20a%20Control.wmvVariables%20and%20a%20Control.wmv

http://www.goldiesroom.org/Multimedia/Movie_Clips/99%20Labs/http://www.goldiesroom.org/Multimedia/Movie_Clips/99%20Labs/Proving%20a%20Round%20World.wmvProving%20a%20Round%20World.wmv

http://www.goldiesroom.org/Multimedia/Movie_Clips/99%20Labs/http://www.goldiesroom.org/Multimedia/Movie_Clips/99%20Labs/Disproving%20a%20Claim.wmvDisproving%20a%20Claim.wmv

http://www.youtube.com/watch?v=oz8eDCC2PgQhttp://www.youtube.com/watch?v=oz8eDCC2PgQ