The Scientific Method

Mr. Knowles

Anatomy and Physiology

Liberty Senior High School

Early Anatomists• Hippocrates- Greek

philosopher and physician, 400 B.C.

• Hippocratic Oath

• Four “Humours” of the body.

• Observations, little Experimentation

Greek and Roman Surgical Instruments

Early Black Bag

Claudius Galenus (Galen)• Roman anatomist

during the 1st Century.

• Described the human anatomy in detail.

• Little understanding of physiology.

Galen’s Office

Galen’s Specimens

Vesalius• 16th Century anatomist

who provided exquisite detail of systems.

• Experimentation with domestic animals. To determine function.

• Assumed Galen to be correct; not questioned.

Vesalius at Work!

William Harvey• 17th Century English

anatomist who questioned some of Galen’s conclusions.

• Determined how the CV system worked in 1628 publication.

• Used experimentation to prove CV function.

The Scientific Method

An empirical way of explaining phenomena in

the world.

With what does all good science research begin?

A Question!

21 Questions to Conclusions!

Make a Concept Map to Relate the Following Terms

• Theory

• Hypothesis

• Principle

• Law

See My Concept Map

Click to View

Some Definitions• Law or Fact- a confirmed observation

(direct/or indirect).• Hypothesis- a testable prediction,

based on prior knowledge and experience.

• Theory- a unifying explanation of several facts; a working model.

• Principle- who knows?

Based on our discussion…

What would you call the idea of Spontaneous

Generation?

Germ Theory?

The Role of Hypotheses in Inquiry

• In science, a hypothesis–Is a tentative answer to a well-framed

question, an explanation on trial–Makes predictions that can be tested

Hypothesis• Comes from an observation --->

question or a problem.

• It is a Testable Prediction (Maybe True or False).

• Written as an If __I.V.___, then _D.V.____ statement.

Hypotheses in Everyday Problems

Observations

Questions

Hypothesis # 1:Dead batteries

Hypothesis # 2:Burnt-out bulb

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction

Test does not falsify hypothesis

Test prediction

Test falsifies hypothesisFigure 1.25

Deduction: The “If…then” Logic of Hypothesis-Based Science

• In deductive reasoning:

–The logic flows from the general to the specific.

• If a hypothesis is correct:

–Then we can expect a particular outcome.

Hypothetico-Deductive Reasoning

• Actually written as If… and …then…therefore.

• If …(your hypothesis)… and (planned experiment)…, then… (expected results)…therefore…(conclusion).

Hypothesis must be...• Testable (Falsifiable) (ex.

Absolute Zero---> Molecular Motion Stops)

• Unbiased (ex. Cancer statistics in North America; Utah vs, D.C.)

• Repeatable (ex. Cold Fusion, University of Utah experiment)

Pons and Fleischmann, University of Utah, 1989

An Unbiased Hypothesis?

• Research testing the hypothesis that cell phones--> brain tumors.

• Who funds this work?

• Motorola- the number one manufacturer of cell phones in U.S.

Writing a Hypothesis

Dangerous Breast Implants?

• Do breast implants cause connective tissue disease?

• How would you write a hypothesis?

What’s wrong with this?

The Scientific Method

Designing Controlled Experiments

• Experiments must be designed to test:

–The effect of one variable by testing control groups and experimental groups in a way that cancels the effects of unwanted variables.

• In mimicry– A harmless species resembles a harmful species

Flower fly(non-stinging)

Honeybee (stinging)Figure 1.26

A Case Study in Scientific Inquiry: Investigating Mimicry in Snake

Populations

• In this case study

– Mimicry in king snakes is examined

– The hypothesis predicts that predators in non–coral snake areas will attack king snakes more frequently than will predators that live where coral snakes are present

Scarlet king snake

Scarlet king snake

Key

Range of scarlet king snake

Range of eastern color snake

Eastern coral snake

NorthCarolina

SouthCarolina

Figure 1.27

Field Experiments with Artificial Snakes

• To test this mimicry hypothesis– Researchers made hundreds of artificial snakes, an experimental

group resembling king snakes and a control group of plain brown snakes

(a) Artificial king snake

(b) Brown artificial snake that has been attackedFigure 1.28

• After a given period of time– The researchers collected data that fit a key prediction

Figure 1.29

In areas where coral snakes were present, most attacks were onbrown artificial snakes

Key

% of attacks on artificial king snakes

% of attacks on brown artificial snakes

Field site with artificial snakes

17%

83%

NorthCarolina

SouthCarolina

XX

XX X

XX

X XX

XXXX

In areas where coral snakeswere absent, most attacks

were on artificial king snakes

84%

16%

Key

If a hypothesis meets all criteria, then...

• Test hypothesis by experimentation.

• After repeated testing, a hypothesis may support a Scientific Theory.

A Theory must ...

• Describe a real phenomenon (always true).

• Make accurate predictions about the world.

• Be dynamic, able to be refined or updated.

Model Building in Science• Models of ideas, structures, and processes

– Help us understand scientific phenomena and make predictions

To lungs To body

Rightartium

Rightartium

Rightventricle

Right ventricle

Fromlungs

Frombody

Figure 1.30

What is the difference between a fact and a theory?

• The Theory of Gravity:

Ex. Newton and Einstein- both contributed to the theory.

new information--->revision of theory.

Scientific Method• Problem

• Hypothesis

• Materials

• Procedure

1. Number steps

2. Control Group/Experimental group

3. Constants

• Data/Results

1. Title

2. Label axis: x-axis - IV

y-axis - DV

• Conclusions

(including discussion of errors)