Scientific Method

Fact or Fiction? Turtle eggs develop into males in cold temperatures and females in warmer temperatures Insect-eating bats can eat as many as 3000 insects in one night The average American teenager eats about 1815 pounds of food each year

Believe it or not, all of those statements are true facts! To gather knowledge about nature, scientists OBSERVE the world around them. They then come up with ideas to EXPLAIN what they observed Then, they perform EXPERIMENTS to test their explanations This is “good science”!

Tell Me More! Science is a tool. –It is also a “process” Think about this question: “I have high cholesterol, what should I do?” –Take cholesterol lowering medication? –Consult your astrologer? –Pray to the god Baal and sacrifice a goat? NO! Use the Scientific Method!

Steps in the Scientific Method ObserveObserve ProblemProblem HypothesisHypothesis –Predict ExperimentExperiment DataData –Data Collection –Data Analysis ConclusionConclusion Repeat!Repeat!

Steps in the Scientific Method OH! PLEASE HAVE EXTRA DELICIOUS CANDY READY ! ObserveObserve ProblemProblem HypothesisHypothesis –Predict ExperimentExperiment DataData –Data Collection –Data Analysis ConclusionConclusion Repeat!Repeat!

Every Day Science Observations An example of an every-day science observation might be: noticing that many salamanders near a pond have curved, not straight, tails

Hypothesis A suggested solution to (reason for) the problem or observation –An Educated Guess Must be testable Predicts an outcome

Hypothesis An example of a hypothesis might be: the salamanders have curved tails due to pollution in the soil where they live the salamanders have curved tails due to pollution in the soil where they live YUCK

Experiment An experiment is a procedure set up to test the hypothesis

Controlled Experiment Make sure only ONE factor affects the results. The factor being tested/changed is the Independent/ Manipulated Variable

Experiment A good (valid) science experiment tests a single variable that can be measured against a control. A Control is the same experiment, leaving out the variable.

Controlled Experiments Controlled experiments are situations where all factors are the same between two test subjects, except for the single experimental variable.

Independent Variable The independent variable is the one factor that is changed in the experiment – Sometimes called the “manipulated” variable

Scientific Experiments Follow Rules An experimenter changes one factor and observes or measures what happens.

The factor that is changed by the experimenter is the independent variable. –This is what is “manipulated” The factor that is measured or observed is called the dependent variable. –What “ happens ” DEPENDS on what the experimenter changed!

What is the Purpose of a Control? Controls are NOT being tested Controls are used for COMPARISON Controls sometimes use PLACEBOs

One more thing… it is best to make several trials and use a large sample group with each independent variable.

Data Results of the experiment are recorded Must be organized Can be organized into charts, tables, or graphs

Conclusion The answer to the hypothesis based on the data obtained from the experiment Does the data support or not support your hypothesis?

Repeat/Retest In order to verify the results, experiments must be repeated / retested

Theories Vs.Laws What does the word “Theory” mean?What does the word “Theory” mean? “A well tested / supported guess” (Webster’s Dictionary) Is a Theory less than a Law?Is a Theory less than a Law? “Evolution is a theory, it is not a fact.” When a theory has been tested many times and is accepted as absolute fact, it becomes a Law.When a theory has been tested many times and is accepted as absolute fact, it becomes a Law.

So?????? A successful, well tested hypothesis eventually becomes a Scientific Theory. A successful, well tested, well accepted Theory becomes a Scientific Law.

Yup.....So?????? The Scientific Method is used to ensure that the process goes right... And there are no errors... Because errors can cause odd things to occur! Experiment in Error