The Nature of Science and The Scientific Method Chemistry – Lincoln High School Mrs. Cameron

The Purpose of Science: Is to create models that explain natural phenomena. Model = theory = explanation

So you’ve decided to study chemistry – Or have you?

~You have always been a scientist ~

~ Haven’t you? ~

So when did “mankind” begin to study science?

Beginnings of Science. Science has roots in philosophy FlMgZcIBR0M/Th2Jv3u11XI/AAAAAAAAAOE/G9gdYevwCEk/s1600/Le+penseur.jpg

Philosophical questions: philosophy.columbian.gwu.edu%252Fphilosophical-questions%3B556%3B703

Socrates – “academios” (grape arbor) Socrates net/digging/images /2010_09_06_Wildf lower_Center/Grap e_arbor.JPG

We learn by generalizing. We come to knowledge through logic. Syllogisms: Three statement arguments – (2 statements organized to make a third.) Girls have long hair. Mary has long hair. Mary must be a girl. Socrates h8vgMY4Y/TC9jS3MwwKI/AA AAAAAAASY/NdpkyzjRafE/s1 600/61.jpg

Plato - Socrate’s student. - What is reality? Anything that changes is not real. The only way to acquire knowledge is to study what is real. x320.jpg

What are things that change in this world? Is there anything that doesn’t change?

Aristotle Reality changes so therefore Knowledge must change also. Reality is experienced, physical reality. There is no limit to what you can know.

Science vs Philosophy Science Ask questions that can be tested Scientific thinking involves –observations –defining a problem –construction of explanations –evaluation of possible explanations or solutions to the problem Philosophy Asks questions that may or may not be able to be tested. Philosophical thinking is open ended May be based on opinion

Albert Einstein – There is a limit to what you can know. And here’s why….

The Nature of Science – Inductive and Deductive Reasoning and The Scientific Method

– Start with general principle, see if individual fits generality. Ex. Mathematical Proofs, Is Pluto a planet? Deduction or Deductive Reasoning / &biw=1440&bih=775&tbm=isch&tbo=u&source=u niv&sa=X&ei=eZ8JVPmFGOrCsATR2oGoBQ&ve d=0CEMQsAQ#facrc=_&imgdii=_&imgrc=XquaM _Sjr7OeiM%253A%3BYekJOp8nnlRooM%3Bhttp %253A%252F%252Fwww.magicalears.com%25 2Fclipart%252FClassic%252520Characters%252 FPluto%252Fpluto001.gif%3Bhttp%253A%252F %252Fwww.magicalears.com%252Fclipart%252 FClassic%252520Characters%252FPluto%252F %3B1043%3B589

Faulty Deductions: mgdii=_&imgrc=lG0wiya_oikhcM%253A%3BHB4xtbvr3XJKMM%3Bhttp%253A%252F%252F1.bp.blogspot.com%252F_RS7AxrV5uuc%252FSdjEiptsQQI%252FAAAAAAAAADI%252FIj 1YAAl-CbM%252Fs400%252Fpenguin_syllogism.jpg%3Bhttp%253A%252F%252Fkjwtokjournal.blogspot.com%252F2009_04_01_archive.html%3B355%3B400

– Specific observations lead to generalizations. Ex. Space ship visiting the high school Caveman story - The generalization has to fit the observations…. Induction or Inductive Reasoning

When do you have enough examples or observations? Need all examples to reach certainty. Never reach “certainty” Inductive leap – Can’t examine all examples. This means the generalization must change when an observation does not fit the generalization.

Models A model is the best possible explanation which accounts for all observed phenomenon and has predictability. 1)An unanswered question means change the model. 2)Predictability is the test of a good or “true” model. 3)Occham’s Razor – of 2 possible explanations, choose the simpler.

If the purpose of science is to create models that explain natural phenomena, then by it’s very nature it changes. You can’t equate science with God, or faith or things that don’t change. You can’t equate science with the truth.

Science is not philosophy – it is based on observations and uses an organized, methodical method to explain the natural world.

The Scientific Method Uses both inductive and deductive reasoning.

The Scientific Method A method to solve problems A method to make models A method to answer questions A method to explain natural phenomena

Steps in the Scientific Method 1.Observe 2. Ask a question or state a problem based on observations 3. State a hypothesis (must be able to be tested!)

4. Test the hypothesis by designing and performing experiments. 5. Analyze results 6. Share the results and conclusions with others.

The scientific method is a guideline – sometimes scientists do things out of order! Both inductive and deductive reasoning are used at different times. Experiment design follows guidelines too.

Experiment Design Independent Variable – condition changed by experimenter Dependent Variable – responds to the independent variable Control – holds everything but the variables constant so you can see if the variable has an effect on the outcome of the experiment.

Observations and Evidence Objective – State only what really happens (no bias or opinion) Repeatable – When the same procedure is repeated by others, they obtain the same results.